I got a CNC router with the intention to use it for making guitar and bass parts. I have been prototyping with cheap pine just to make sure that my 3D models and the carving process are working properly. Pine is great to see the size and shape of a fingerboard, but it's unusable in even a test instrument and is way too soft to hammer frets into. Whats a cheap, easily-available wood that I could use for testing?
