This is my own easy; print and glue, single shot loom/elastic band shooter! I printed mine at 200 microns at 15% infill. No support structure required! In the picture you can see four pink loom bands which gives the trigger tension, this is compulsory, just set them like I have in the picture. There is a knock at the end of the 'barrel', you pull the loom band from there, across the length of the gun and over the trigger. Then you are ready to fire! Any upgrade suggestions greatly appreciated :)