In looking at other parts of the forum I saw some past dirt sifters and thought I'd post my take on it.
I tried the box setup and found it too slow for the literal tons of dirt and rocks I needed to sift here. So when a friend gave me a plastic 55gal barrel the dim bulb went on. I decided to make more of a leaky cement mixer setup. I had most of the materials except the 3/4" conduit. Luckily it's pretty inexpensive. I cut two circles out of 3/4" plywood to strengthen the bottom of the barrel where the drive would be and screwed them together with deck screws. To hold the end of the barrel up I had a bunch of these sealed bearing rollers that are off a conveyor drive at the place I used to work. They had no need of them when they scrapped the conveyor so I got a bucket full of them and I use them for everything. They have some kind of heavy duty vulcanized rubber with a groove in them for the drive belt, perfect for going in the top seam of the drum to support it on the front. I also had tons of 1/2" rod that I used for the braces that hold the upper rollers and eventually to hold the improvised plastic tarp/dust shield away from the top of the drum. The holes were cut with a hole saw and then covered with 1/4" wire cloth to do the sifting.
I also had the 1" shaft and pillow block bearing along with the cull belt drum that I cut in half to make an adapter for the HFT handheld pipe threader that now powers the sifter.
the top three pix were the early stages to see if it would dump like I hoped. And I'd not yet tried it out so it was hand powered with the handwheel off the HFT roller I used to roll the bottom 3/4" pipe crossbrace and the ring that holds the upper support rollers. When I took off the handwheel I also had to weld on handles to move the whole thing. It actually is quite easy to move because it's pretty light and when tilted back on the handles it's balanced. That was just dumb luck.