First of all you need medicine bottle, a big pen, some peewee. In case you wish you can also use a compressor fitted with a ball valve throttle. Now take the medicine bottle and make two holes of 1/4 inches into both ends. Once you have done this, you shall get cap with a hole and a bottom with a hole at its end. Now take your big pen and cut a piece of a one and half inch from it. Take this smaller piece of the pen and stick it at the end of the medicine bottle. Stick it so that only a little portion is inside the bottle. Now take the larger piece of the pen and then stick it to the cap of the medicine bottle. Stick it as much inside as the previous one. Now attach the cap to the bottle. Your gun is now ready. Now if you want you can blow in the air inside but first add the peewee into the bottle. You can also use the compressor to blow the air. For this you have to attach a reducer piece using a valve to the bottle. After this you have to tape the reducer very tightly to the bottle. Now attach this valve to the compressor. Put some peewee in the bottle. Now charge your compressor to 90 psi. Now aim at your target and then shoot. That's it.