Made it for my son but im going to test it out today for him..
It has classifier a built in fluid bed and the foam at the end is for buoyancy ... for the areas where you have to create a little flow...
I have used similar before...i got the idea again after watching gold fall out of my mates grabstake mckirk... im going to give it a thorough test ...dump it anywhere with flow and over feed it! I will let ya all know how it goes i feel pretty confident.