I made one back in the 70's, inspired by Gary Davis and Sam McGee. I took a cheap six string that had been stepped on, and cut a hole in the front face with a jig saw, large enough to accommodate a banjo head. I bought a banjo head and tailpiece from Elderly instruments, and added wood shims to raise the head up to the correct level. I took care to make sure the bridge would be the correct distance to keep the octaves correct. This is a very primitive way to make an instrument, but it worked. It was good for picking ragtime, very muddy if strummed. Perhaps the higher strings mentioned above would improve that... Brad http://pages.about.com/bsondahl