Flat sanding cawl

[Christophe Mineau]

In luthery work, for the purpose of leveling the frets of a fingerboard, you need a dead flat sanding cawl.
Here is how to make one out of wood and glass.

I first shape a wooden handle block, planned as flat as possible.
Then I cut with a standard glass cutter three layers of the same size out of a scrap piece of window glass, maybe 3mm thick.
All these, glued together using CA glue (works very well on glass)
After the glue has cured, the edges are smoothed using a dremel and a diamond wheel.
Eventually, I have stuck a sheet of 1000 grit sandpaper using double side tape.