Hey, well today i just figured out how to do this and i'll tell you right now. this is the Most entertaining Semi auto-matic airsoft gun you'll EVER make in your entire life, AND it's Really cheap and will cost you about 2 to 4 dollars :P so besides all this . lets get sarted, first you need to purchase a cap gun, anything that looks like mine really, it needs to fit 6mm bb's in the chamber, or clip, or what ever you prefer to call it, either way they need to fit, so check before you buy one, and just go to the dollar store to find one, they're very cheap, oh and mine is already done in this picture. so this is basicly what it should look like when your done, but for now. lets just say it's a cap gun.