Player-made Structures

Caisson
A Caisson is a structure that allows characters to create shafts through water and empty space. It is simple to construct: simply place a row of blocks 4 wide underneath the character then mine out the center 2 blocks and repeat. If you wish to capture some water for the shaft you are creating, create a U shape out of blocks first and then continue normally.

Hellevator
thumb|right|310px|A Player showing the Hellevator 'Hellevator', also known as 'Hellvator', is the Terraria jargon for a drop from the main land to the underworld (Hell). It is a portmanteau of Hell and elevator, for obvious reasons. Usually at the bottom of a Hellevator is Water, since it removes fall damage, but another way you can successfully survive is by using a Grappling Hook, or Ivy Whip, however these methods require precise activation to avoid fall damage. A Lucky Horseshoe or Rocket Boots is also favorable because the former negates all fall damage whilst the latter is able to prevent it with a bit of hovering, however it can be more difficult to find these than a Grappling Hook. Another useful method to lessen fall damage in the Hellevator is to place cobwebs at strategic points. They will stop a player's fall, but caution must be taken, as the cobwebs can be easily removed by the careless swing of a weapon.

Water Docks
Water docks are used in hellevators to prevent water from travelling with you all the way to hell. The lower part can easily be taken out to let the water flow, and maybe end up in lava, becoming an efficient way to farm obsidian.

To build a vertical water dock, just start digging stone at one of the sides (right or left) parallel to the water tunnel, letting an air vent so the water can't keep going. Next, keep digging following the path of your water tunnel, this way you'll be holding all the water all the time you want. By removing the lower part of the dock, you can open and close the dock, letting all or just part of the water flow.

Liquid Filling
Liquid Filling is a process where you destroy the existing liquid (water or lava, either works) in the way of your hellevator in order to continue straight down with nothing in your way. It works with lava as well as water. To liquid fill, just place any block of material (stone, dirt, mud, etc.) in the liquid you are trying to hellevate through. After you place a row of blocks in the liquid below you, simply mine downward and the liquid will be gone. Sand can be used to quickly fill in the columns below your platform, but is not recommended for use as the walls of the shaft when going through liquid. Doing so risks flooding the shaft if a mistake is made, and replacing it with some sturdier and less dangerous material is tricky.