To build this you need to buy * 2x DC motor - ø30mm - 12V - 2mm shaft * 2x Threaded rods M5 x 75cm or longer * 2x Ring M5 * 4x Nut M5 * 8x AA batteries * Some electrical wire with a plug * 4x Battery inserts (springs and pushers) as you find in every AA battery compartiment Print all the parts in PLA with with 50% infill. When printing use support, but if your slicer allows you to set support for yourself, please don't use support in the holes for the threaded rods. If you can't prevent your slicer from placing support there, use a drill size M5 to remove the support structures. My advice, Print every part as a separate print job. I didn't have any succes with multiple parts on the bed. All together the printing costed me about 150+ hours After printing: Prepare the threaded rods by placing the a nut at the end. Seen from the GoPro mounting hole, insert the threaded rods so that the nut falls in place and then start sliding all the parts on top. (It's like a puzzle, It only fits one way) Some parts need some glue. I used the most transparant hot glue I could get because this type of hot glue is removable with a few drops of Isopropyl alcohol if you have to remove the glue. When everything is put together, make the battery box. There are two parts, a top and a bottom part. You will need springs and holders from another battery box (or if you can buy them separately, do so). I used glue to get the things in place (See the video if you don't know what parts I am talking about). Then solder the wires to the last spring and holder and glue that in place to. the wire comes out the only opening there is in the battery box and can be glued in there as well. Connect the wire to a plug and the other and of the plug with wire to the motors (one should spin clockwise, the other counter clockwise) and you are done. I wish you all the pleasure in the world with your Nerf Rifle. A little P.S.: In some countries the barrel should be bright orange !!! Don't let your kids play with something that is not allowed in your country !!!