Ok, so here is the regulator. It will adapt to 16g and 20g canisters out of the box, though now that I've tested it, the cartridges don't seem to have a very long life span. Maybe 2-4 minutes for continuous pulsing of our 10cm (1cm diameter) McKibbens, with only 1-2 minutes of high-quality pressure. It's fine for us because we are using it for a one-time inflation. The regulator has a compatible fitting that will allow you to adapt it to a larger canister, but I haven't checked which. I have not tested it with a paintball canister, which I believe get up to 3000 PSI. The regulator itself is quite heavy for soft robot stuff, and so I've considered machining one from plastic, but I don't have the time or skill at the moment. To slightly decrease the mass, you can take off the dial gauge and put a plug in instead. I haven't tried, but you might be able to take off the screw top if you remove the rubber sticker pad on top. This might save up to 20 or 50 grams. The output range is nominally 0-40 PSI, but realistically, it appears it doesn't go above 25 or 30 PSI. The output of a 16g CO2 cartridge is about 100psi (I didn't measure it rigorously).

The barb we are using out of the regulator is a 1/8" NPTF elbow barbed fitting, part # 53525k11 at McMaster.com. I preferred the elbow to keep the tubes more in line with the canister. I couldn't find any smaller 1/8" NPTF fittings. I use a 1/4" Tygon tube with a 1/8" wall on the barb, part # 6516T23 at McMaster. At the end of this, I use a 1/4" barbed Luer lock fitting, part # 51525K126at McMaster, which allows me to easily switch between 1/4", 1/8", and 1/16" tube sizes using mating Luer fittings. You can also find step-down barbed fittings on McMaster.

In practice, the canister-side pressure fluctuates quite a bit during use due to the elastic response of the gas when the valves open and close. This can get pretty severe as you add more actuators to the line, but performance seemed to stay up pretty well.

From there, we use the custom control valves based on the Parker X-valve and a Honeywell pressure sensor, but if you want cheap, using two of these 2-way valves can give you a full inflate, deflate, and hold state. If you'd like more info on our custom control valves, I'll send across a link for a paper I wrote on them.

If you'd like to know more, PM me and perhaps we can connect IRL.