How to Make a Mini Dart Gun w/Multiple Configurations

I’ve been playing with the idea of what cool things I might be able to do with soda bottle preforms for a little while now and this is what I’ve come up with. The dart gun in this video uses two different firing methods that are commonly used in larger potato cannons, a pneumatic firing option, as well as a simple combustion option. A coaxial piston valve is my personal favorite mechanism for these sort of projects, and this video shows how it works quite well through the clear chamber. For the combustion d