As promised, here are a few pics of the fret slot cutting machine I am working on. It is very simple, but requires a great deal of precision to make sure the saw guide remains absolutely at right angles to the new fretboard.

Here are some of the parts I have made so far. The pattern fretboard will mount in the back, aligned by pins, not yet installed.

This is the carriage. The slot rides over the rail. It is a snug fit, so that the blade guide will be at right angles to the fretboard.

Here is a partial assembly. The new fretboard will be raised close to the carriage. The pattern fretboard will be mounted under the carriage at the back. The oval window in the carriage is where I can see the fret slots on the patter. I mounted a thin piece of wire inside to get the carriage aligned perfectly over the groove.