Ive made a little spud gun that uses Deo as fuel. Its combustion chamber is made out of a Plastik Cup.
Step 1: Materials
-Drill with Drill-Bits
-Electic igniter (you can get them out of lighters)
Step 2: Making the Gun 1
Then Glue the tube in the hole
Step 3: Making the Gun 2
Then glue the ignitor in the hole and stick the wire through the hole so that it almost touches the metal part inside the cup.
Your Spud gun is Done!
Step 4: Using It
Close it up
put a piece of paper in the tube
Press on the ignitor and see your Bullet Fly away