I thought it would be sweet to have a mini wrist-mounted flamethrower. It does not shoot liquid fuel, just propane.

The design is very simple. It consists of two gas lines connected to a propane canister. One line has a needle valve to control gas flow. It serves as the pilot light to keep the flame going. The second line is attached to a solenoid valve that is wired to a button in my other hand. Once pushed, it opens the gas line fully. Extremely simple but very very fun to play with.