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