This has been designed in sketchup. I havent tried to print it yet, nor have i converted it in Meshlab to an STL. Im currently working on my Fusion Reactor 3D Printer so this is on hold. www.FusionPrinters.com If you print one out, im curious how it does. ThanksTakes 2 rubber bands, there is a tray for the pennies on top. There are two sides that fit together. There is a hammer that is locked by a trigger. The only parts needed, are some screws to hold together, 2 rubber bands, and some pennies to shoot!!! Let me know if you are working on this or need some help with the file.