here is a neat little gun I built to help with how hard it is on you're finger to light that tiny pizo ignighter. it fires airsoft bbs at about 200-250 fps do not try to build this gun unless you have experience with mini potato guns or else you will have a very hard time building it and trouble shooting. this gun is very sensitive on what it uses for fuel.
UPDATE the pizo ignighter broke so I am going to try my luck with a camera flash. also I have upgraded the barrel to a metal one I got out of an old airsoft gun. and last using butane nearly doubles the power of the gun and is sounds like a 22cal rifle going off
I have stopped using the cap right now I just hold my finger over the hole and it works just fine if not better
Step 1: Get All Youre Stuff
1 old hot glue gun
2 good hot glue gun that works
3 bic pen all taken apart so all you have left is the pen body
4 a highlighter
5 a pen cap
6 pizo ighightor
7 2 thumbtacks
8 some kind of brass part from a cars brake line?
8 nut glued into bottlecap
1 phillips screwdriver
1 multy tool
Step 2: Take Apart Hot Glue Gun
remove all the stuff in you're hot glue gun keeping the trigger and glue the pezo ignighter so when you pull the trigger the pezo clicks
Step 3: Combustion Chamber and Barrle
cut the highlighted in half and cut the end off the pen cap(the purple thing) then use it to hold the pen to the highlighted. and glue together glue the brake line fitting on the cut end of the highlighter. and enter thumbtacks. on both sides. I used one screw so I can tune the spark gap size and cut cap tip so barrel can fit thru it this will hold it secure to the hot glue gun.
Step 4: Bringing Hot Glue Gun to Combustion Chamber
hook up all wiring from the pizo to the combustion chamber and click it. you should see a spark jump from the pins. if not then make it work. and set the combustion chamber and barrel in there new home. DO NOT GLUE SO YOU CAN REMOVE IT TO CLEAN YOURE GUN. and don't chop off the end of the barrel. it will reduce the power of you're gun and it wont look like an uzi anymore.
Step 5: Put the Case Together
put the case together and bolt it down and look in the back where the bolt pops out. and pull the trigger do you see a spark if you do than good. if not then take it all back apart and find the problem.
Step 6: Time for the Test.
put propane or butane down the back of the gun. I prefer butane. screw on the back and drop something down the barrel like a 6mm bb. point at something and fire. if nothing happens press 5 more times open cap and lightly blow into back and try again.