SpudFiles

preloaded with a shirt? I don't think i follow how this works. Something has to move in order to allow the air to escape in the barrell? Or is that delrin "flexible enough" to make this concept a diaphram?

Delrin isn't flexible, it moves backward.

sorry was confused as everything was "glues in place" Except for that part i see.

If you had to make it like in the diagram and fit the T-shirt in the coaxial barrel the cart would have to be enormous so not really practical. You can however use the cart as an air source, loading in the t-shirt first.

Given your compact space requirements, including a secondary chamber and a main air source isn't really going to fit with standard parts.

You could make a variation of Brian's pirate pistol, but that would be single shot.