What has been the most noticable difference within your tank since using the algae scrubber? You definitely thought this out well, so i assume you really see a benefit with it's addition.
I've only had it running about 3 weeks and I made the mistake of having my pump turn off with the lights for the first 2 weeks. I seeded the screen with some turf algae from a friend and one week later the screen is covered. Tank hasn't really seen the benefits yet in that short time.
Any interest in making these to sell?
Well, if I made them professionally I would change a lot about it to reduce the cost. Without giving away all my ideas; lets just say that I wouldn't have so much PVC plumbing, and I'd likely design my own lights. I'm a Mechanical Design Engineer and the project is pretty simple to re-design for production. That being said, there are multitudes of vendors that make stuff for aquariums and they would likely sink me quickly unless I had a lot of cash to inject into the project for design, test, tooling, marketing, packaging, distribution, shows, etc.
I would be interested in doing a new novel design as a partner with a company or individual investor. I think there is some real potential for a design patent on a particular embodiment, but the basic Algae Turf Scrubber utility patent was granted in the 1980's. So the only protection from copycats would be a design patent which only covers the ornamental design (basically the look but not the function). I have 11 patents on other projects I've worked on so I'm not new to this rodeo.
In answer to your question, I think Turbo Aquatics does a nice job of making waterfall ATS's on a craft level for purchase. I don't think I'd want to spend my free time in the garage building ATS units for sale though. I'd sure be glad to help you with advice via phone or email though.
I thought it would be better to put the plans out there kind of like shareware so everyone who wants to build one can have a nice guide to go by. The plans I have on my website are a very detailed set of dimensioned drawings with complete bills of materials for every part in the ATS. You could easily take these to any plastic shop and have them build one for you. Or, you could order the plastic pre-cut and polished and just glue it together yourself.