I would think with my Fabrication background that your design would be dictated on what form of water injection you would be using. As an example of laying your sluice down into the flowing water of a stream or river..and then a gravity type water feeder would be drastically different. I have thought about this allot, and have come to the conclusion that I could build and design a sluice much better and drastically cheaper than what I have seen commercially available. A simple Aluminum sheet bent into a 3 sided rectangular trough, with having as many as 3-4 different sections that would be slightly larger on the bottom of each trough. This way you could easily slide all 3-4 section into each other for transporting to the dig site. A simple Aluminum flat bar TIG welded on each section so that they would hold their shape and also design it so that they would slide out evenly but also have a stop and lock position. You could then design in some riffles or whatever your choice of turbulent action that you wanted. This type design would not weigh much at all for the back country hiker, etc. And if you wanted an elevated standing trough then you can still use the Aluminum but have it to where the legs slipped into larger sized tubing for easy break down. A then fold-able water tight container could be designed and used for a gravity type unit, maybe line it with simple plastic tarp type material for ease of carry into the back country. But if weight and carry distance are not an issue then something a little more robust would be even easier to design and build. I just can't see spending the kinds of money that these commercial rigs go for, the cheaper ones seems way too short for any percentage of gold recovery. Also and a big thought, at the end of your sluice trough to have some sort of container that captures all the material and water that goes thru your sluice. surely a container at this position would help in capturing whatever the sluice did not recover. But this tank at the very end would get the fine grained Gold sand and would simply fall down to the bottom of such tank/container.
