Local to me dry ice sells for $30-$35 per 50Lbs, blocks are (10"x10"x11" ) otherwise "nuggets" are available for the same price 60-70 cents a pound (assuming quantity's of 50lbs or more)'
I roughly figure (biased on the info here) that you can pull 2 extractions out of a QP (112gr) of trim using 50lbs of dry ice ($35 worth). Half the dry ice (25lbs) and 1 cup ethanol? for each pass..
If you were to use a 4" sch 40 steel pipe it would need to be atleast 6' long to accommodate this volume (perhaps a bit more depending on how fine your "nuggets" are).
You have convinced me that the Nitrox is unnecessary. (to be honest I had a brain fart earlier worrying about sub critical temperatures inside the vessel from gassing off during the extraction, but I'm not stoned yet today and see how silly that was) it seems only the pressure gauge from a nitrox tank (4500psi) and the burst valve from a Co2 tank (2500-3000psi) would be required (so you know in advance if you need to take cover) Also the small shut off valve of course. The hardest part will be drilling and tapping the holes..
Swimming pools and warm temperatures aren't as common up this end of things so I have a feeling the heat tape and some sort of thermostat would be necessary (otherwise converting an old gas hot water heater might work).
there is 45 grams of ethanol added to that formula.
45 grams at 0.789 grams per milliliter would equal 57 milliliters, almost 2 ounces or 1/4 cup (for each oz of trim?)
Why the ethanol though? Why so much? Does it make for a less selective extraction?
This is just surprising the way I'm seeing it, after an initial investment of $200 (or less) you could be processing your trimmings for under $5 an oz... You could even make multiple extraction vestals and process a pound (or more) at a time using a single converted water heater.