Instructables.com, a How-to website invites people to join a contest by sending their homemade inventions. Check out one of the videos sent by a contestant, the 25mm pneumatic action sniper, it is really cool I think, though I do not recommend you to try it at home, since it could be dangerous and illegal in some ares. The home made sniper has custom bolt-action mechanism and a sniper scope on the top that cost at about $40. Enjoy it!

Instructables | via Gizmodo