Holsters aren't that hard to design. Start with a large piece of heavy paper and fold it over the gun, drawing a line and presssing hard so the other side of the piece has a depressed line to follow, leave and extra 3/8 inch for sewing it together. perhaps a half inch, if you intend to lace it together with thong strips. Remember to leave a piece, a few inches wide, to fold over for a belt loop at the top. I have made three or four from scratch. It does take leather that is heavier than black smith sides. You probably want something about 8oz. Oak tanned shoulder cuts are ok and cheaper but not as blemish free as a whole side. Chrome tanned is a bit stiffer to work with.