Doc is looking old...perhaps the big C? Oddly I prototyped something similar to this after using the pro pan for a while. Admittedly not the same but similar, and I see they encountered some of the design issues I also had to solve, but they are onto something. I couldnt find a material light enough so I modified mine to be inclusive in a tub, otherwise you find yourself craning as doc was in his demo. I used wings on my slots, and covered mesh over the opening. The grizzly is a terrible idea, you need mesh otherwise the broad flat stones get in, but flow from the bottom is excellent for clays. I'm glad I have dated video of my build its similar, but i went with stainless more rigid for less profile, and you only need to shake one end not both so its big enough to put two shovel fills in to process without the hard labor. I like it though, the pyramid was a great start this is just taking it a step further.