This bass is a 21" scale, with a piezo saddle mounted in an adjustable bridge. The soundhole is just for looks. The strings are metal-wound Kalas. The fretboard is cut out of the ugliest piece of wood I ever received. For such a small neck, I managed to cut around most of the ugly, and the result isn't half bad.
I made this little mitre box. It goes in 5-degree steps from 0 to 45 degrees. I don't know if that will actually be useful, but it gives me something to play with. Although I made it with the saw shown, I would use it with a fret saw, which is narrower and runs in the slots nicely. The important thing is not that the angles are super accurate, but that they are repeatable. I think.