Great design an a lot of fun to play with. I tried wood first which I don't recommend because the holes needed to be cleared to fit from the larger nozzle print. I then tried PETG Which worked a lot better and fit well. But the small Pins on the geared wheel and the stopper arm snapped on first fire. Didn't matter, they are just stoppers and it still works great. Just maybe suggesting try a Wooden dowel instead of the printed pin for those parts for added durability. Just a suggestion. Loved it and still having fun with it. Thanks for sharing.