Back in the 1970's a friend and me made a few of these out of some old brass strips we found in the back of the store at work. The first two were one each so we could take a banjo each out into the wild when tramping and hunting. Later we built a few for friends. When I modeled this I was looking at some 4mm aluminum offcuts at work and thought they would be good for banjo bodies. I could cut them to size in the guillotine and run the blanks through the CNC turret punch for the holes and made some quite easily so i made a drawing of the body, but never got around to it before I retired.
There are a few good guitar and violin models on grabcad also some models of hurdy gurdy's