[SVD]

Technically you can run the Classic or Artisian with the little tiny pocket CO2 cylinders (not sure if the Nitro will work or not - might require too high a pressure), but they'll only run for a very few minutes. Even the extremely gas frugal Palm Control will only run for, what, about 15 minutes? out of your pocket.

It's still cool that you can do that.

Go to the more standard 20oz paintball gun tank, however, and a Classic will run 3 - 4 hours. I know because at first I only ran my Classic off of CO2. Later I got a regulator so I could run if off of my compressor as well and Steve gave me the little quick-connects so I can switch back and forth at will (better to have those than to keep taking the hoses off of the barbs).

While you can't fit a 20oz tank in most pockets, there is a belt clip setup (or at least there used to be) sold for running air tools (mostly nailers) off of CO2. All you really need is a pouch of about the right size with a belt loop/clip so it would be easy to rig. The problem I have with that is I have just NO touch at all engraving standing up. I know, I've tried. If you've got a table to set your vise / work on, you can set your CO2 canister on it as well.