7mm Fret worked perfectly for me
I print these with the following settings
99% Infill (100% if you don't use gyroid)
0.15mm layer lines (0.2 is fine)
Supports on Build Plate ONLY
The author remixed this model.
I made the fret physically taller without affecting the lower half where the keyswitch attaches. I personally used the 7mm on my WhamCaster, but the 8mm felt ok as well