Here is a simple fret depth checking gauge for those who use standard guitar frets...I decided to make this a separate discussion from the fret jig thread for obvious reasons.
Very simply, take a 3 to 4 inch long piece of standard fret wire and bend it into an 'L' shape with the 'inside' of the 'L' being the fret surface itself. In other words, bend it backwards on itself like this:
Once bent backwards in an approximate 45 to 90 degree angle, file the tangs off of the fret 'bottom edge' with a small file, that is, the edge that is seated into the neck. You don't want the tangs on the fret which will make it easier to slide in and out of the fret cutout line on the neck. Then, you can use the 'fret depth gauge' to check the dept of your fret cuts every few strokes like this:
Check both sides or ends of the cut in the neck to ensure proper depth and consistency on both sides of the neck at each fret position.