Glad to see this subject come up! I just started building my own cyclone, nearly a Bill Pentz design except that it isn't the size he recommends. It will be a 4" mini version that I'll use with an old 1-1/2 hp Delta dust collector motor/impeller from craigslist. This will be my super shop vac until I can make the full size 6", as well as a test unit for fasteners, shaping method, etc.
I have drawn Bill's entire cyclone layout in AutoCAD with his guidence. I've also found a terrific local metal shop that can laser cut 24 ga galvanized (from CAD files). Not sure what the laser cut price would be since I just walked in to get the material ($15), but my guess is that it wouldn't add too much to the material price.
Would there be enough interest here to go in together and get a number of sets cut? I'd also be interested in getting together for a few weeks to build the things. We could share tips and jigs, maybe develop a similar ductwork strategy, and so on.
I know there's enough talent in this group that we could make quality units cheaper than can be bought. If I could, I'd buy the ClearVue, but that is way outside of my price range right now. My super shop vac is going to come in around $95 + filters, if we could build full size units in the $300 range that would definitely work better with my budgeting committee.