Haha, good concept, but hold that thought...I've been looking at what you guys have been doing with springs and clothespins, and I decided that I'm going to make one (To start with) of these kinda things. Just gotta wait to go to the hardware store tomorrow. Just had to satisfy my creativity with modeling an idea in 3-d.
I figure since you guys have been posting 3-d models of stuff you plan on making, I'd post my concept also.
I'm thinking 1 1/4" SCH 40 Pvc Pipe for the main compression chamber, and 1/2" CPVC Pipe for the barrel/charging rod. (Yes, They are compatable if you do some modding) Then use your clothespin trigger system with a iron trigger, then use a spring clip made with acrylic and wood. (Already got this from a failed experiment). I figure if it's not too big, I can use it as a sidearm, or if it turns out too big, put a stock on it and use it as a primary. That is, IF it gets decent range when I'm finished.
I've got one nearly identical to that in the works. About another week or so and it'll be released commercially.