In the earliest days of my prospecting adventures I invented the Bushmaster 2012. A sluice box of sorts, consisting of layers of screen mesh overlaid weeping tile...
Poorly assembled out of duck tape, found timber, etc, it was the best I could do. I'd counselled a female friend, who promised an abundance of power tools, upon showing up to avail myself of them I discovered that most of them seemed to involve "AA" and "AAA" batteries. Oooops. Clearly I had misread the situation. Nonetheless, with hammer and nails and a bit of savoir-faire, the Bushmaster 2012 was assembled...
Despite appearances, it actually worked pretty good, collecting the fine gold out of the Athabasca River, problems I later ran into involved having to completely destroy the box to recover the fine gold from the weeping tile (really, in the end, not a big deal, but it lacked practicality), and the fact that while the gold accumulated in the weeping tile, the diamonds would just slide right off of the screen mesh. Probably I lost millions.
First attempts, not bad, but not good when analyzed in terms of re-usability or the recovery of things other than fine gold...