Maker's mark

A maker's mark can be crafted using an iron ingot and two dyes, the dyes affect the color of the stamp.

Using a stamp (without an item in the offhand) the UI for designing the stamp opens up. Click to paint in the boxes to design the stamp.

Once done a designed stamp might look like this.

Using a stamp with a piece of equipment in the other hand will stamp the equipment, changing its tooltip.