Not finding anything yet I am going to build my consept of what it should be. I will creat a card table size frame with a sheet metal chute underneath, that will carry off worm and eggs plus casting materials that will fit between 1/4 inch mesh of hardware cloth. On the open top there will be a sliding rectangle frame, which will hold about 2 gallons of mixed materials, that will be shifted and tapped to the end to dislodge the smaller portions of the worm, soil mix through the mesh. Of course I exspect to have to experiment with mesh size.