i'm actually in the paintball industry, and i have access to various equipments which i think is great to share with you guys.
i use a paintball HPA tank (high pressure air) the small (48ci) tank that attaches to a paintball marker.
this is always fitted with a regulator, output usually to 800psi (some are low output, 450psi).
from there, using parts from my spares bin, i have a SmartParts Ion (a popular entry level electro pneumatic paintball marker) regulator (most electro marker regs will work) that does between 0-300psi.
i use a macro hose from the tank output into the reg's input, from the reg output i have a remote line (fitted with a 0-300psi gauge) that is about 1meter coiled length, that connects to the nipple on the launcher's hose.
the regulator is adjustable via a hex nut on the bottom.
point of all this is, i have a setup that is relatively cheap, safe, and it works as well as a Scuba setup without the weight!
the tank's about 1.5kg / 3.1lb
i've not tested extensively yet, but i reckon it'll fill a 12liter WRocket to 120psi a couple times

will post pics when i got the time
