In addition to Gatos, Osos, Rosas and Infinitos, I've tried building a few other guitar-like instruments, as well as some non-stringed instruments.
La Piña Tenor Ukulele
This is a tenor ukulele with a pineapple carved back made from a piece of mahogany with a spruce soundboard. I played it for a summer then decided to sell it. Hopefully the new owner is enjoying it.
I used a Merlin 2 mini-angle grinder to do the carving. (If you get one of these, throw away the mini-chain saw. It is too dangerous to use.)