Would this work?

http://www.instructables.com/id/Trommel-Compost-Sifter/

I made a harvester out of a 20(?) gallon oil barrel with cut-outs and the screen inside. It spins on wheels that are mounted to a frame that straddles my wheelbarrow. VC needs to be very dry to use it (or the VC just rolls up into turds) and the worms get hung up in the 1/4" screen between the screen and the drum (which is where they die). Also cocoons and baby worms fall through the screen, so the "finished" VC still has to go into an incubator to give the cocoons time to hatch. Basically, this was a complete waste of my time and about $14 for the screen at LoweÂs. I no longer use it since perfecting the self-harvesting worm systems.