This is a toy, of a slingshotpistol. You have to add screws 5pcs M4x20mm and 2pcs M4x10mm. 7pcs inserts M4x8,1mm to melt into the holes, if the holes are to small use a 5,5mm drill. 2pcs M3x35 or 40mm for the triggerpieces. 2 springs for the trigger, use springs from 2 pens and cut to a good length. Slingshotrubberbandtube 10-12cm. Magnet 5x2mm. Steelbar 4x75mm. Braided fishing line to secure the rubberband to screws and the line for the steelbar. Polyester line aprox. 30cm. If You are using a 0,4mm nozzle print with 4 walls and 0,2mm layerheight. Glue the grips on to the pistol. If the springs are to weak You have to push the trigger forward when loading to get it to lock in position. Then use a steelball 6-8mm and put into the hole on the top and on to the magnet in the barrel. Aim and shoot, enjoy. You can use the extender to get more power without changing rubberbands. Do not forget to change to longer screws. Inspiration from DIY Crossbow on Youtube https://www.youtube.com/watch?v=ZUFx3ggL_2o