This is an adaptation of the P201 Rubber band gun. The original design is by oggcraft.jp I have endeavoured to create a version of the P201 that could be produced with my Printrbot+. Here is the result, a 10 shot, semi automatic version. Thanks to oggcraft.jp for allowing me to publish this design.Overview This gun has an overall length of 340mm ( ~13.5" ), so unless you have a large bed printer, you are going to have to make the long bits in 2 parts and glue them together. The STL files that I have uploaded will all fit on a 200mm bed. I may have been able to make a more aesthetically pleasing join, but as it was my first attempt I was going for a cut that would hold together. Printing Print all the STL files. I printed all parts with 4 solid layers and 40% infill, 0,25mm layer thickness. For both of the body parts, RBG_Body-Front.stl and RBG_Body-Rear.stl, you will need to print with supports. Parts RBG-Release-L.stl and RBG-Release-R.stl may be printed at the same time. Make sure that you have the pieces the right way up on the bed as they have a raised portion on the side that attaches to the bolt. Assembly Clean supports off both body parts and pay extra attention to cleaning up the supported side of the notches. The slide pieces will need to travel along the side of the notches to release the rubber bands. Glue the rear and front body parts together. I used superglue. Make sure that the pieces are aligned straight so that the trigger slide will operate correctly. Next fit the ratchet into the slide-end. I drilled all the holes out to 3mm and used a cut off 3mm screw to hold the ratchet on its pivot point in the slide-end. I then used a smooth 3mm bar in the other hole on the ratchet that rests against the underneath of the slide end. I glued the smooth bar in place. With the ratchet fitted in place in the slide-end, you now need to glue the slide-end to the end of the slide (the bit with the trigger on the end). There are a raised flats on the inside of the slide-end that will align on the slide. The slide end should be ~10mm onto the end of the slide and 1mm above the bottom of the slide (refer to the photo of the inside of the gun). You need to make sure that the trigger can slide backwards and forwards at least 12mm. You may need to file the end of the slide end and inside of the trigger to make sure that you have the desired clearance. Once the slide-end is glued on the slide, fit a rubber band from the rear of the slide end, over the ratchet pins and into the lower notch. This will hold the ratchet up. Fit the bolt and position the ratchet into a notch on the bolt. I then filed grooves into the slide-end to allow the ratchet to fully engage into the notches. Now with the bolt on the very first notch engaged into the ratchet, I glued the left and right release pieces onto the bolt. I aligned the edge of the release to be at the bottom of the first rubber band notch (furtherest from rear) on the top of the gun. Next load the gun with 10 rubber bands, starting with the rear most notch and working to the front. Fire the gun and check that it is releasing each rubber band as expected and that the ratchet is engaging on the next slot each time that the trigger is released. If anything is not working correctly, it should be pretty obvious where the problem is, do any adjustments that it needs to make it fire correctly. Finally glue the two remaining side covers onto the gun making sure not to jam any of the moving pieces. Enjoy!