Would this work?

[Dave Bagwill]

This measures the thickness of non-metallic coatings, like on cars.
Up to 2 mm.
Would it work measuring the thickness of wood, if you held a magnetic material against the top on the inside?

http://www.amazon.com/AGPtek%C2%AE-Digi ... B00IG0MEUA

[John Parchem]

The meter most likely measures the distance it is from the metal panel. Putting something inside the guitar would not give you a relevant reading.

[Dave Bagwill]

A piece of metal that could be detected by the magnet wouldn't work? Dang.

[John Parchem]

actually up to 2mm it would measure the wood. My apology I though you wanted to measure your finish.

[ken cierp]

If you could find one that measures thicker, like 4mm you could have a check point where you know exactly how thick the wood is, then place a metal plate in that location. Take the measurement minus the known wood thickness = paint thickness.

Much hassle -- I simply guess, leaning toward applying too much