Oh hey that's me! I blew my 15 minutes of internet fame on a throwaway comment on a github issue :-)

I'm thinking of making custom Kentucky Long Rifles personally. Tons of handcrafting - really woodworking since most makers use manufactured barrels and/or lockwork, and I believe there's a market for them. From a US Federal perspective, they're not even legally firearms so I don't think you'd have to worry much about red tape.