The chisel is a tool to carve messages via a method similar to writing signs. It was added in Public Beta 30. They can be smithed and reforged using iron.
Carving[]
When you right click on a stone- or wood-block, you are able to edit a close-up of the block, similar to sign-writing. Each carving costs one of your chisel's initial 100 durability.
Like vanilla signs, the carving occupies the space in front of the block, where it's fixed to. Therefore, you can't place anything else there.
There is also a second variant, the moon-chisel, which writes in glowing letters that only appear at night, if you are near it. The max distance from which it can be seen is about nine blocks.
Crafting[]
The normal chisel is crafted with any stick and an iron ingot.
Once obtained, it can be upgraded to a moon-chisel by adding some ithildin on any Elven or Dwarvish crafting table. You can even use an already damaged chisel for that:
Cleaning[]
The block's surface can be cleared, by just left-clicking with anything except for a chisel.
Example[]
This message is only visible at night, if you are quite near it.