I also plan on polishing the inside of the 1/2'' barrel so the objects move with less friction.
I do realize that there will be a significant time lapse during the release of pressure threw the .177 barrel i will be making it capable of multiple shots much like a BBMG.
YES, I KNOW THIS IS VERY DANGEROUS, DONT DO AS I DO!!!!
also: Noise is not a factor the louder the better.
Barrel length not set yet.
I Just picked up a 2000 psi regulator for my tank

The rendering:
I made this in cinema 4d, because I've seen way to many done in paint...(the gauge is not UV mapped)
I plan on building the the tank-less version because i don't have a paintball tank or a way to fill one.
They are not exactly to scale, nor will it be galvanised pipe.
This is simple model of the final product so you readers can get a feel for what I'm trying to create.
Tell me what you think?