Pressure Plates

Pressure Plate is used to activate mechanisms though wires when someone steps on it. The plate sit partially hidden on top of blocks.

Pressure Plate allow you to see laid wires when held.

Plates can be purchased from a Mechanic or taken from a natural source -- starting from 1.1 they are randomly generated on the map during creating of worlds.

Pressure Plates are a great tool for opening and closing doors without having to click on them.