That kind of method is what I'm offering an alternative to with my Prepetual Motion Goodness Extractor. I admire the ingenuity I've seen in these "one-pass/total-loss" solutions -- and I've seen them used -- but I've got a little paranoia about the smell and the fumes, as well as the economy and safety of using all that butane, or alcohol, for that matter. I don't think I can move all the THC out of the donor stuff in one pass, and I think it calls a lot of attention to myself to shoot a couple or three 8oz cans of butane into my backyard air.

But my Prepetual Motion Goodness Extractor With a few modifications will do much more than a prepetual butane extraction. It's a still. So by separating the expansion chamber from the collection chamber you can separate alcohol from cheap vodka. Although more expensive than butane, it stinks less, is safer, and it's still cheaper (and stronger) than everclear. The modifications basically amount to removing the extraction chamber and routing the flow from the bottom of the coil to a pop bottle, and using a heatable, sealable vessel like a pressure cooker for an expansion chamber instead of the mason jar. Of course you need a better heat source than a mixing bowl of tap water, too. Butane boils at about +30f, but pure alcohol boils around +170f, and impure vodka might take +185f to build up enough vapor to run to the coil.

Also, if you add valves in the right places you can trap the solvent in the coil, change out the donor stuff or reconfigure the device, and restart the process without a significant loss of solvent. I have valves at the top and bottom of the extraction chamber, top and bottom of the coil, and at both of the ports in the expansion chamber lid. I can separate the solvent from the goodness and drip it into a glass bottle when I'm done, put it in the deepfreeze, and reuse it next time. This control, economy, and better safety makes the effort worthwhile. It's also fun to watch!