Guide:Making money

Money is an essential part of Terraria, as it allows the player to buy items from NPCs. There are 4 types of coins; Platinum, Gold, Silver, and Copper. Platinum being the most valuable and copper being the least valuable

There are several ways to earn money:
 * Killing monsters and bosses.
 * Selling items to NPCs.
 * Finding coins in pots and chests.
 * Picking them up from the pet Leprechaun o'Fyffe.

Crafting and Farming
The following tables show different ways of making money. In this case, they compare the resources needed to earn in profit. For example, crafting and selling Ale is very simple since it only requires one item, Sand Blocks. However, it does require a lot of repetitive digging (50 blocks). Instead, some people might prefer selling Fish Bowls, since harvesting Goldfish is more interesting. You can also buy lesser mana potions, craft lesser health potions, making Restoration potions and selling them.


 * See also: Guide:Gardening


 * Far left column - item sold to the NPC
 * Middle column - raw ingredients required for crafting
 * Far right column - Notes

Note: the Sand Blocks are not used directly; you need to craft them into Bottled Water or Mugs first.

Note: Armor Statue sell for 10 silver 20 copper

Accessories
Mana Flower:96 silver coins profit.Profit may vary depending on modifier.Uses two Lesser Mana Potions (merchant) 1 glowing mushroom (mushroom biome) 1 nature's gift (underground jungle)

Eye of Cthulhu and Eater of Worlds/Brain of Cthulhu
Demonite Ore (Corrupt World) or Crimtane Ore (Crimson World) occurs sometimes in the wild, but the best source is from defeating Eater of Worlds (Corrupt World) (or) Brain of Cthulhu (Crimson World) or the Eye of Cthulhu. You'll need all the best equipment you can get, plus some decent armor. Check out the Eye of Cthulhu guide and the Eater of Worlds guide for some great ways to make these fights go easier. Once you fight them a couple times and craft everything you can from the spoils, all the rest is more money for you. Another upside is that once have all the demonite you want and you're nowhere close to hardmode you can sell demonite for around 7 gold a stack.

Your payoff here is Demonite Ore that sells for each, a great profit indeed and well worth any ammunition and potions the player may have expended for the fight, and you can make even more profit by crafting ingots out of the ore. Eater of Worlds also drops Shadow Scales worth a piece. If the player has spawned in a Crimson World, then they will fight the Brain of Cthulhu, who drops Crimtane Ore worth and Tissue Samples worth  each. Crimtane Ore sells for a fair bit more than Demonite, so the player can get more profit if they have spawned in a Crimson World. The drops are randomized just like other enemy drops, so your mileage may vary. Even if you get horrific luck with drops, running bosses is well worth the time and effort and can be a lot more exciting than life on a potion farm.

By the time the player reaches high tier, they will have a defense of around 25. This statistic drastically reduces the damage the EoW and BoC do, and the player can easily destroy the two bosses. With lots of ammunition and good weapons (such as the Minishark or Night's Edge) they can make short work of both bosses, making more money than they could ever need. It is possible to defeat EoC eight or more times in one night, which sums up to.

Expected Profit: Varies

Selling Muskets
Another way to make money is selling guns (Musket). First, you need to create a new world, and then look for Shadow Orbs, break them, and Collect Ball O' Hurt and/or Muskets. You can sell muskets for (Some muskets have more value, ). This method is very fast and you can even make more money by selling everything you get by killing the Eater of Worlds to get a lot of money.

The Destroyer
In hardmode, the player can fight The Destroyer and easily win if they have good enough gear (Mythril/Orichalcum armor is advised as a minimum). After crafting everything you need with his Souls of Might, you can just sell them. They sell for each, and you would normally get 20-40 of them per kill, which would sell for roughly. Besides, The Destroyer also drops 15-30 Hallowed Bars, which can be sold for per piece for a maximum of. However, these can be crafted into any type of Helmet, for an extra per 12 bars. It is possible to kill it up to 10 times in one night with the help of the Golden Shower and any of the starter hardmode sets, using the Headgear for extra magical damage. However, using the Paladin's Hammer the destroyer can be killed in less than 10 seconds if you find it while curled up, allowing massive profits to be made.

Expected Profit: per run.
 * Note: Before 1.2.3, Gungnirs made from hallowed bars sell for per piece (more or less depending on modifier), and gave a large profit per run. However, its price now is only , lower than the cost of 12 hallowed bar


 * In 1.2.3 sell price of Souls of Might also has been lowered to, so you'll get less money now. To compensate that you can craft Light Discs from the bars and souls, which will almost double their value; you will also need some Souls of Light for that, but if you fight the boss in Hallowed biome you'll get more than enough.

Queen bee bashing
The queen bee becomes very easy to fight with hardmode weapons, especially end-game weapons like The Horseman's Blade. The QBs drop  per kill, and it is possible to kill one in about 20 seconds only with powerful enough stuff. An Unreal Tactical Shotgun with Crystal Bullets in full Shroomite Armor and max damage accessories (with damage modifiers) can kill the Queen Bee in 2-3 shots. Therefore, it is possible to make a minute, or  an hour, not counting the queen bee's numerous drops. Also, the Queen Bee doesn't need to be summoned during the day/night, and only needs to be summoned (not fought) in a jungle. In fine, Abeemination is rather easy to craft, as honey is dropped from the queen bee, stingers are dropped from the numerous hornets in the jungle, and honey blocks can be farmed renewably. However, you'll need to plunder beehives to get the non-renewable Hive.

With the addition of the Bee Armor set, Bee Wax itself sells for apiece. The Bee Headgear sells for at the cost of only 8 Bee Wax (or   total).

Wall of Flesh
Using post-hardmode gear, you can farm the Wall of Flesh quickly and cheaply with a Flamethrower or a Golden Shower (Golden Shower is preferable since farming gel is harder than waiting for the Mana to recharge, barring access to a Slime Statue gel-farm.). Since you can summon him in day or night you can make more money than other bosses, unfortunately the amount of summons is based on guide respawns and voodoo demon spawns. Drops just for killing him, a Pwnhammer which sells for about , and a random other item which sells for.

Expected Profit: Varies (Estimated per day)

Golem
When you get the Picksaw from the Golem, you can move the altar located inside the jungle temple. You can make a box with Spiky Ball traps to easily farm the Golem. Sit back, and enjoy the loot!

Expected Profit: plus the item(s) he drops.

Statue farming
The following statues spawn items or monsters (which don't drop coins, but will drop items), allowing you to make gold without even working for it:
 * Bomb Statue
 * Slime Statue
 * Jellyfish Statue
 * Skeleton Statue
 * Piranha Statue
 * Fish Statue
 * Shark Statue

One of the easiest setups for a statue farm is to connect the statue to 1 or more 1 Second Timers (or a Crab Engine). Except for the bomb statue you should then either place the statue in a shallow layer of lava (recommended) or connect a few Dart Traps to kill the spawned monsters. Once you click the switch, all you have to do is stand still, or even return from time to time to collect the rewards. (Except for Bomb Statues, which will stop spawning when there are 3 Bombs, so you need to stay close to collect the bombs.)

In addition, using Bunny Statues and Fish Statues during a Blood Moon will spawn their corrupt counterparts, which rarely drop Bunny Hoods. The normal spawn limit for Statues is 3 mobs at a time, but when Goldfish and Bunnies change to their corrupt counterparts, they don't count towards the Statue's spawn limit, so you can have seemingly endless amounts of them on screen. This does not affect their actual spawn rate.

Expected profit (when using a Crab Engine and Lava):
 * The Jellyfish Statue will yield about per hour, and will fill your inventory in about 13 minutes. This makes the Jellyfish statue probably the most effective one if you resell the items quickly.
 * The Bomb Statue will yield about per hour, and will fill your inventory in about 46 mintues.
 * The Skeleton Statue will yield about per hour, and will fill your inventory in about 18 minutes.
 * The Bat Statue will yield about  per hour and will fill your inventory in about 46 minutes.
 * The Piranha Statue will yield about  per hour and will fill your inventory in about 3 hours.
 * The Slime Statue will yield about  per hour and will fill your inventory in about 4.6 hours.
 * The Bunny Statue will yield about  per hour and will fill your inventory in about 12.5 hours
 * The Fish Statue, Bird Statue and Crab Statue will yield about per hour and will fill your inventory in about 6.4 days.
 * Sharks and mimics are slow to kill, limiting the efectiveness of such farms. These statues,howewer,can be used to farm ectoplasm (as both monsters have more than 100 health points),which sell for each. If one has already defeated Plantera and looted Lihzahrd Temple from traps,this method can yield about ,or even more if you're lucky.

Fastest money generation is with the Jellyfish Statue, but after 2 hours items will start despawning. If you plan to AFK farm for more than 4 hours, it is better to farm Bombs, which start to despawn only after 7 hours. Bombs are optimal until you farm for 18 days, when banners from Fish/Bird/Crab start to become more profitable. At that point however, it would be better to turn off your computer and save electricity.

Killing Monsters
Once in Hardmode you can buy Gold Dust to craft items which will increase the amount of money monsters drop on death.

Slime Staff Farming
If you have a Lucky Coin and Slime Staff (Slime statues do drop Slime Staffs) you can farm for money very easily at the rate of about 10 Gold/Minute. With full tiki or spooky armor, create a space in the Lihzarhd Temple where you can stand in a box in an open space with all of the Lihzarhds crowing below you. Then summon all of the slimes you can with your tiki armor. The slimes hit very quickly and only do about 1 damage a hit, with each hit giving chance to drop several gold coins due to the Lucky Coin.

Unicorns
Once you enable Hardmode, it may be a good idea to kill Unicorns. They drop Unicorn Horns, which sell for 30 Silver Coins each. It's pretty effective because unicorns spawn quite regularly in The Hallow.

Mimics
It's very effective to kill Mimics because they drop 10 Gold Coins by death, and you can sell the items they drop for even more money. And it's easy to kill them by using a continuously swinging sword with enough knockback to keep the Mimic at distance or killing them using a ranged weapon from a distance. If one has acces to Gold Bullets or Flask of Gold,it will be wise to use them,as it will raise money dropped by Mimics even to 24 Gold Coins.

Hardmode Dungeon
A very fun and effective way to grind money is to gear up with endgame gear and farm the Hardmode Dungeon. After killing Plantera go in there and farm all the monsters you see. Armored Bones drop over ten silver each, and they are so common that you can easily rack up a lot of money fast. Also, sell the Ectoplasm and drops you don't need for even more money. In one hour, you might be able to get five platinum with water candles and battle potions and maybe even a lucky Blood Moon. Another way to use the dungeon for money-making is to use a farm. Lihzahrd Temple-type traps can prove to be very useful in this method, and will make fighting in the dungeon a lot safer.

Hardmode Spider Nest
An extremely effective way to get money is in the Hardmode Spider Nest with a strong sword such as a Cutlass or Excalibur and a Water Candle and/or Battle Potion. Black Recluses drop directly, Spider Fangs which can be sold for  each, and Poison Staffs that sell for  each, which varies with modifiers that can change the sell value dramatically.

Expected Profit: Roughly  per minute

Handling money
When trying to accumulate coins, there are many small steps to take that can make the task much less of a chore:
 * Get a Chest / Piggy Bank / Safe to use as your "stash" and get into the habit of throwing all your coins into it whenever possible. Regular "banking" minimizes the loss of coins from Death, as death drops at least half the coins in a player's Inventory.
 * To quickly get money from your stash to your inventory, just throw it on the ground and pick it up from there. The game will convert all the coins into largest possible denominations. If you've got nothing but coins in your stash chest/piggy bank, the "Loot All" option is even faster.
 * As of 1.0.6, using the "Quick Stack" button at your stash will automatically convert stacks of 100 or more coins into the next largest denomination, provided you have a coin of any type already in your "bank".

What to keep
The following items can all be used to craft more profitable items, and should not be sold as-is or discarded:
 * Lesser Healing Potions and Lesser Mana Potions: Keep these around to eventually make full-sized Healing Potions and Mana Potions out of, then Restoration Potions if you can.
 * Wood: Wood has no value when sold on its own, but is used for so many profitable items that it should be saved. Even when you don't have anything to combine it with you can just make Wooden Chairs (or Wooden Tables) and sell them, earning for each piece of wood, or if you have access to a sawmill you can craft weapon racks, which sell for ; since a weapon rack costs 10 wood to craft, each piece of wood is worth.
 * Stone Blocks: Plentiful and useful for building Houses and stopping the spread of Corruption (pre-hardmode), but you can always get more. Craft 100 excess Stone Blocks into a Statue and sell them for, a 0.6/block return.
 * Sand: Crafts Glass, then crafts Mugs, which then crafts Ale, which sells for each. Glass is also needed to make Bottles, a necessary ingredient for potions. You'll also find quite a few bottles in chests, so keep those as well. In hardmode, normal sand becomes somewhat of a rarity due to corruption and hallow spreading everywhere and turning all deserts to ebonsand and pearlsand respectively.
 * Clay: Crafts Pink Vases. They sell for each, which equals 3.5 copper per block.
 * Cobwebs: If you're saving up for Necro armor, keep in mind that you don't need too many of these -- a full set of the armor requires only 135 cobwebs. All the rest should be turned into Silk and sold for a net profit of per cobweb.
 * Vile Mushrooms: Crafts Vile Powder which sells for per bag, or  per mushroom.
 * Goldfish: 2 Goldfish and 1 Bottled Water crafts the Fish Bowl, which sells for a whopping each.
 * Lens: 6 lenses allows you to craft a Suspicious Looking Eye and summon the Eye of Cthulhu for big cash rewards.
 * Glowing Mushroom: Glowing Mushrooms can be kept to make Lesser Healing Potions in to Healing Potions, as well as Lesser Mana Potions into Mana Potions; increasing value.

What to discard
These things are going to clog your inventory to no end, and are almost impossible to make money off of. If your inventory is full and you're deciding what items to take home and sell, go ahead and trash these:
 * Dirt Blocks: Useful for growing some plants and handy as a plentiful building material, but will never be more than that. You can always get more.
 * Mud Blocks: Mud is used to grow mushroom grass or chlorophyte, both of which are valuable, or as a building material. Mud can be crafted from dirt when standing in or near water.
 * Glowsticks: Useful only for temporarily lighting underwater areas. Not worth much, either.
 * Wooden Arrows: Very common in pots and chests, only pick them up if you'll use them as ammo, to craft better arrows, or you've got nothing more valuable to keep in that inventory slot.
 * Shuriken and Throwing Knives: You'll find a lot of these in chests underground, but in such small amounts that they're not worth carrying. If you've got a decent ranged weapon you won't see much benefit from carrying these.

What to sell
These raw items are worth selling as-is. When your inventory is full and you need to choose, try to keep these around and toss something else:
 * Accessories and Weapons: The less you use something, the less likely you are to use it in the future. Most accessories will sell for great amounts of coins and will not stack, so go ahead and sell them. As stated before, if you can find one thing you can find ten more. If you've got multiple copies of an accessory then you'll probably find many more copies in the future, so don't worry about something being gone forever. Possible exceptions are swords required to craft the Night's Edge, which you may want to keep duplicates of so you'll still have use of them even after sacrificing them to craft it.
 * Ores: Excess ores can be sold once you're kitted out and your house is decorated from top to bottom. It may however, still be a good idea to keep your gold, copper, and iron ores because you will need these for hardmode items later on. Meteorite ore should be crafted to bars before selling for better profit. Note that iron/lead bars are required to craft hardmode boss summoning items.
 * Collecting and selling Crystal Shards, which you can find in the underground hallow. They are easy to collect and sell for lots of money - a hundred being worth.

Chest Duplicating
There is another fast way to earn money, but you will need most of your inventory empty to earn the most money. You will place any Chest on 2 Active Stone Block and some Wire connecting the blocks with a Pressure Plate. Then place 1 of any item in the chest and then if made correctly, the chest will still be there but it will break into multiple chests. You can place a row of Active Stone Blocks with multiple chests and then do the process again and you should earn about and  every 99 chests; not normal chests but gold chests and shadow chests. As of the Thanksgiving update on mobile, this method will not work.

Marshmallows
All you need to farm Marshmallows is a campfire, a Merchant in a snow biome, and lot of wood. You buy a marshmallow, put it on a stick, roast it, and sell it for twice as much as you bought it for. Note: Roasting takes time, and Marshmallows on sticks do not stack, so this is not a good way to make a lot of money fast.

Torches
Farming Torches requires Wood and Gel.

Torches are just about the easiest and simplest thing to farm. Wood is plentiful and can be easily regrown, and a long, flat surface outside can serve as both a tree farm and a place to kill slimes for gel. Simply flatten out a huge expanse of dirt, wait for it to grass over, and start planting acorns. Torches have the added bonus of being able to be crafted anywhere, and what you don't sell remains useful throughout the game so you'll likely be making lots of torches anyway.

Torches sell for each and are produced in stacks of 3. The limiting factor is going to be Gel, i.e. you'll run out of it before running out of wood. Gel sells for each. Wood is worth each (if crafted into Chairs) Crafting torches therefore "costs" and will yield   ( for each torch), for a profit of.

Each stack of 99 Gel together with 99 Wood will create 297 Torches. The crafting will net you  more than selling the chairs and raw gel.

Torches can sell for quite a bit more when upgraded to tiki torches, but this diminishes your wood resources a lot faster. Each wood spent on a tiki torch would be worth, the torches themselves worth. The total profit from each tiki torch is.

Another fast way to make money using only Wood is to buy some Torches from the Merchant for, then craft them into Tiki Torch and sell them back for , making a profit of for only three wood.

Lesser Healing Potions
To produce these you'll need: Once you've gotten a little further into the game this becomes a good option. If you haven't yet started a farm for Glowing Mushrooms then making Lesser potions is still quite good, and will suffice until you can start growing shrooms. As with torches, the fruits of your labor will be useful to you throughout the game: having a lot of healing potions on hand is always good.
 * An Alchemy Station
 * Sand, for making bottles
 * Mushrooms
 * Gel, by the truckload

Expected Profit: and  per 30

You'll need twice as much gel as mushrooms, but mushrooms are harder to come by unless you specifically farm for them. See the gardening guide for more on that. Two gel are only worth, a mushroom is , and 2 bottles are for a total cost of  for 2 potions. They sell for each, giving a net profit of  for 2 potions, or   for a stack of 30.

Tree farms work well for farming gel, as the flat open spaces seem to spawn tons of green and blue slimes.

Healing Potions
A Healing Potion requires:
 * 2 Lesser Healing Potions
 * 1 Glowing Mushroom

Advantages:
 * Healing potions are extremely profitable, selling for each.
 * Glowing mushrooms are easy to farm in large quantities, requiring very little maintenance compared to regular mushroom farms (which must be regularly "weeded")
 * Healing potions are more effective at healing than their lesser equivalents, and most players will be making them for this purpose anyway.

Expected Profit: and  per 30

As mentioned earlier, 2 Lessers cost in raw materials, and Glowing mushrooms are  each. Subtract this from the sale price and our anticipated profit becomes   per potion, or   for a stack of 30. Actual profit is slightly higher, as Lesser Healing Potions can be found in pots and chests all over the place, as well as bosses and dungeon shelves.

Tip: Never buy your Lesser potions from the Merchant. Lesser Healing Potions cost when purchased from the merchant. If you purchase Lesser potions and sell Healing potions, you will spend and gain, a net loss of  per potion you craft.

Shine and Night Owl Potions
Shine Potions and Night Owl Potions use the following: Both kinds of potions sell for just like Healing Potions. They are an excellent source of income to supplement a Potion economy, as they use largely the same ingredients as healing potions and the additional ingredients are easy to find. Daybloom and Daybloom Seeds can be found everywhere on the surface as long as they're harvested in the daytime, while Blinkroot can be found everywhere underground. Night Owl Potions are useful to make before you find Glowing Mushrooms, while Shine Potions use all the spare Glowing Mushrooms leftover from the Healing Potions.
 * An Alchemy Station
 * Sand, to eventually transform into Bottled Water
 * Daybloom Seeds and a place to grow them, either grass or clay pots
 * Glowing Mushrooms or Blinkroot Seeds

Expected Profit:  per 30

The cost in ingredients is higher, but this balances with the fact that all the ingredients are so easy to farm. Daybloom and Blinkroot is particularly easy to find and grow, and is almost more plentiful in the wild than standard mushrooms. Both herbs are each, glowing mushrooms are, and the bottle of water is. This gets you  per Shine potion in profit, or   for 30. Night Owl Potions net  per potion, by contrast, so if you're overflowing with both Glowing Mushrooms and the fast-growing Blinkroot, make the Shine potions and either sell the leftover Blinkroot or combine it with Cactus to make Swiftness Potion.

Obsidian Skulls
Obsidian is worthless on its own, but you can make Obsidian Skulls from it. They require 20 Obsidian per Skull. You'll need: If using a generator you'll also need: You need about 2 1/2 stacks of Obsidian for a full set of molten gear, so you're likely to be farming this anyway. The most common way is to grab Obsidian as you can find pockets of lava underground and leading water to it from above, then mining from underwater. The Earthwelling technique is a great method that requires a bit more preparation but is easier to mine once it's done, especially for very large lava pockets. Finally there's the Obsidian generator, which is outlined here. Players may or may not agree with the ethics of using a generator, but regardless of how you feel it's a very efficient way to get lots of Obsidian in a hurry.
 * A large portion of Lava
 * A source of Water
 * A Nightmare Pickaxe or better
 * At least one Bucket

Expected Profit:  per 250 Obsidian minimum, more if you get lucky modifiers.

Skulls sell for each, resulting in   per chunk of Obsidian, putting it in the top tier of ores. Every so often, you may get a skull with a modifier on it; they sell for more than ordinary skulls. Obsidian Skulls don't stack, so to avoid a lot of trips back and forth just make a spare furnace and set it down within range of a selling NPC. Once you're in the buy/sell menu you can scroll down your crafting list to make skulls and immediately drop them into the NPC's inventory to sell them.

Ectoplasm
Expected Profit:   per stack of 99 ectoplasm

As of 1.2, enemies in the Hardmode Dungeon (after killing Plantera), when killed, have a chance to turn into Dungeon Spirits. They drop 1 or 2 Ectoplasm each, which sells for each. If you get a large amount, you can easily profit, as each dungeon spirit drops a couple of Ectoplasm, and that makes it easy to make tons of gold. You can also craft them into Ghost Wings, which will give you more profit ( each, where only 10 ectoplasm worth and 20 Soul of Flight worth ). The only hard part is farming the Ectoplasm, as Hardmode Dungeon enemies are stronger than the average enemy. It takes time, but it's worth it. You could, however, wire a chest statue or a shark statue to a mob grinder in the dungeon, both sharks and mimics can become dungeon spirits.

Glowing Mushrooms
Expected Profit: Per 250 Mushrooms, or,   Per 999 Mushrooms

Its very easy, get a sword that goes above your head (Shortswords dont work), Some Mushroom grass seeds, and some Mud. You can also use other blocks to make it easier for you. Get the Mud, and place it like a box, 5x#, you can make it as wide as you want, And make a floor of mud 3 blocks below it, Then another floor of mud 3 blocks above it. So you can fit through it like a tunnel. Keep going up Floor Box Floor box until you end with a box, then use the mushroom grass seeds on all the mud, connect the boxes and floors to make it spread quicker. In 1.2, Glowing mushrooms grow on the surface (Above 0 on the depth meter) Along with Mushroom trees growing on their own, so that's even easier to get more glowing mushrooms.

Stained glass
if you have any gems, DONT SELL THEM! instead make some glass wall. now take any gem (preferably Amethyst) and make stained glass. each set of 20 pieces of stained glass will sell for. if you find a gem cavern you can easily make.

File duplication
When a character (or world) is created, it is saved as a file on your computer. This means that it can be copied like any other file. The default directory for such files are, though this may change with OS. Characters are stored as .plr files; a character called "Manbearpig" will be saved as "Manbearpig.plr". If this file is copied (into "Manbearpig2.plr", for example) the in-game character selection menu will feature two characters named "Manbearpig". (Note that there is no need to copy "Manbearpig.plr.bak". Also note that the order of the .plr files in the Players-folder is representative for the in-game character list.)

The copy will feature all items held and worn by the original, allowing the player to duplicate money and items by repeatedly copying Manbearpig.plr and deposit the copies' inventories in a storage item in-game. Creating money like this makes it increase exponentially: if you start with and copy it 31 times, you will have a little more than  (1*2=2 (one copy) → 230=1073741824 copper coins = 1073 platinum coins).

Copied character files can afterwards be deleted with no issues arising, though you'll also have to delete each copy's respective .plr.bak file and folder. Though arguably being somewhat cumbersome, this method is convenient as it requires no third-party software.

Mods
External third-party programs (mods) such as TerrariViewer and TEdit can be used to alter character or world files. This means they can be used to make money. For example, the former can be used to fill a character's inventory with coins, while the latter can be used to fill a chest.

Cheating
Set your world to "read-only" while you have all your coins in a chest, then load the world. Take the coins, and exit. Set "read-only" off and play again. The coins you took while the world was "read-only" will be in the chest, and you can take them out. If you had, say, about 50 gold, you could get a platinum, and, if you do it again, you can get 2 platinum. And you can do this method whenever needed to get coins back.

Infinite boss farming
Using a bug on any summoning item and quickly change to other item on the quick bar, the summoning item will not be consumed and can be re-used again (the other item may be consumed instead the summoning item). Doing this you can earn money fast and sell all boss loot. Note: Later doing this, you cannot store on a chest (if forced to store it, the item will disappear), but only to the item you used in the bug.

An example is in this video:

Barrel Duplication
Note: Requires two devices, items have disappeared during attempts. Have two people open a barrel (one person might need to open it before the other). Drop items into the barrel that you wish to duplicate. Both people need to have space in their inventory for items. Both people need to simultaneously hit the button that takes all the loot from the chest. Both people will have whatever was put in the barrel.

Misc tips
An easy way to acquire Coins is to harvest Sand Blocks, craft the sand into Glass then Bottles, and then sell those to an NPC for 4 copper per tile of sand. Crafting Ale via Mugs and a Keg is even more profitable, as it turns 2 sand into 20 copper for an exchange of 10 copper per unit of sand (or 99 silver and 90 copper per full stack).

You can also farm the Eye of Cthulhu for Demonite Ore if you have good enough weapons and armor (The Eye of Cthulhu is spawned using the Suspicious Looking Eye). A single Eye will yield an average of about 50 Demonite Ore each time, selling for 8 silver each (about 4 gold in total). You can also farm the Eater of Worlds, which will net about 10 gold if everything is collected (although it is arguably more difficult to obtain the materials needed to summon it).

You can alternatively farm Skeletron by making new worlds or using a Clothier Voodoo Doll. Unlike the Eye of Cthulhu you don't need to farm any items to summon him. He drops on average 5 gold each time.

Another quite easy way is to make another world, go to the Corruption, locate a Shadow Orb and then use a hammer to break the Shadow Orbs, selling the items you get from them (which is optional). Once you have broken 3 Shadow Orbs the Eater Of Worlds will spawn. Kill him and collect everything. Turn the Demonite Ore into bars, then sell them. One stack of 99 Demonite Bars can sell for 31 Gold Coins. Each world spawns with about 6-11 Shadow Orbs, therefore spawning about 3 Eater Of Worlds, which, in total, would drop about one or two Platinum Coins and a few Gold Coins.

If you have advanced through the game to the point of acquiring a Bucket and Nightmare Pickaxe, you can create an Obsidian Generator to mass-produce Obsidian Skulls. These sell for 54 silver each, so selling just two of them gives you over 1 Gold Coin. With this technique, it is possible to acquire the Minishark, with a price of 35 gold, in half an hour.

In hardmode, traveling to the Underground Hallow and collecting as many Crystal Shards as possible is an extremely efficient way to acquire large amounts of money, as one full stack (consisting of 999 shards) sells for almost 1 platinum and 60 gold coins (16 silver coins per shard), plus it doesn't require any specific early investment or preparation (other than reaching Hardmode itself). Crystals are abundant, easy to locate and mine, and respawn. Killing enemies that appear as you run around the Underground Hallow will let you collect even more coins.

If you possess a Bomb Statue, you can hook it up to a timer and it will continuously produce bomb items, each of which selling for 60 copper. More than one wired statue means more bombs acquired in a shorter amount of time.

If you have a Fish Statue and some wire, hook up the statue to a one second timer and grind the goldfish (NPC). You can get goldfish (item), and rarely, goldfish banners. Selling the goldfish at 1 silver per fish is quite good. there is even a way to sustain the farm by making them kill themselves, with Vile Powder. (As of 1.2.3, goldfish no longer sell for any money making this method invalid and no longer functional.)

Grinding Blue Jellyfish from a Jellyfish Statue may be the best automated money maker. Not only does it drop many glowsticks, but also the very valuable Jellyfish Necklace, which is the most expensive item that can drop from a statue, at 1 gold coin. you will still need a mean to activate the statue and kill the jellyfish, as it won't jump by itself in lava.

please see statue for more information about using statues as farms.

One of the most effective ways to make money is to make Glass Walls. You then take 20 glass walls and any gem to make Stained Glass. Each set of 20 stained glass walls will sell for 1 gold coin.