I currently have 4 mini combustion cannons. I will go from smallest to largest .
#1
*chamber - diameter: 1", length: 2", material: clear orange medicine bottle
*barrel - diameter: 1/4", length: 4 1/2", material: pen tube
*ignition - peizo ignitor
*
#2
*chamber - diameter: 1 1/4", length: 2", material: clear orange medicine bottle
*barrel - diameter: 1/4", length: 4/12", material: pen tube
*ignition - peizo ignitor
#3
*chamber - diameter: 1 1/4", length: 2", material: film canister
*barrel - diameter: 1/4", length: 5 3/4", meterial: one of those tubes that glow sticks come in
*ignition: guts of on of those mini lighnting disks.
#4
*chamber - diameter: 2 1/2", length: 5", material: 8 oz. water bottle
*barrel - diameter: 3/8", length: 6", material: metal tube from a longnose lighter
*ignition - peizo ignitor
Fuel: the first three models use butane from those little see through lighters. the fourth model uses propane. you can use other flammables but I use them for ease of fueling
Ammo: you can use just about anything for the mini models such as tape rolls, spit wads, kleenex (smells bad)
, potato slugs, small wooden stakes wrapped in tape and many other things. for the forth model i found these old darts and unscrewed the tips and wrapped them a little in duct tape. they fit perfectly in the barrel. i shot them at my basement wall and one penetrated almost 1"!!!! in a 2x4 stud 
. i was amazed so i shot it again and it went completly through the drywall and was stuck in the other side of the staircase wall. Igntion: for the first, second, and forth models i used the standard peizo that comes out of a long nose lighter. these types of ignition are very simple you just need 2 nails/screws/thumbtacks... whatever and hook up the 2 wires to the nails and create a gap between them, bingo. for the third model I had originally had a peizo on it but it broke so i came up with something rather intersting. I had this old mini lightning disk (whatever its called) that cracked, so i decided to take it apart. I was thinking of using it as kind of a continuous spark like a stun gun. I was doubtful it would work but I tried it anyway. inside there was a cuircit board with this wierd glass thing in the middle with a wire on it. I cut the wire of and attached it to a thumbtac, I then got another tac and hooked it up to a wire I found and wrapped that wire around a capacitor on the cuircit board. again i was just messin around. I stuck the tacs in the film canister and turned it on. The beast LIVES!!!!!!
. i was pretty surprised it worked. the circuit board also had a switch on it with 3 settings. off - soundsensitive - on. the "sound sensitive" setting was like a BBQ ignitor, one quick spark. it aloud you to make a sound and it would spark, kind of like a clapper lol but the "on" setting was a continuous spark. i taped the whole caboozie on the side and plugged the AC adapter into the wall. voila!I hope you enjoyed my post i will try to get pics of all the launchers soon
happy spudding
King_TaTer
