Here we have a set of drywasher plans. It is of the bellows type also known as a "puffer". This machine is designed to be powered by a gas engine but it could also be hand cranked.
The copy of the plans I have doesn't show an author or copyright so I guess it's OK to put them here.
This thing has too many parts for me to consider building it but here are some thoughts based on my drywashing experience.
The plans don't show any bearings on the crankshaft. I would add sealed ball
bearings at the three points on the crankshaft. Drywashers create a very
unfriendly enviroment for bearings. Ditto for engines - I have seen photos
of the engine separated from the drywasher (and the dust) by 6 feet or
more using a looooong belt. Dust is not good for humans either -
Wear a dust mask!!
I have a small sampling drywasher that uses a different bellows arrangement. The front, back & sides are made of sheet metal. Here are some photos showing how it works: