I built my cyclone based on the plans published by wood Mag some 10 or so years ago I guess. It was easy to build, and the only thing I added was a neutral vane which was not in the original plans. I also made my own impeller and blower. I found the 1 Micron pleated filters at a damaged freight auction house for not much money, and THAT was a lucky find. This has worked great and has handled anything I've thrown at it.
I just wish I had a taller ceiling so I could use a bigger collection barrel. The small barrel is really inconvenient when I'm planing, because the volume of chips is tremendous.