This tool is for focusing on the plane, or cutting bed, of a lasersaur. Use this tool for sheets of paper or other very thin material
This tool is for the Lasersaur, hardware version v14.04b, using a 3" lens with a focal distance of 73.3mm.
To use these, set the bottom of your focusing lens exactly 40mm from the bottom of the tube. Note this is the bottom of the lens, not the bottom of the retaining ring.
These tools have a base offset of 17.3mm (the height of the "plane" tool) + the thickness of the material or half the thickness of the material.