i can't seem to dig it up at the moment & i've been searching for a while now. yes, it was a drum inside a drum design. you have me rethinking that though. 2 flat screen on a frame & a sheet of glass below that would probably be easier to construct. then just card the material across each screen or make it detachable from the bottom of the machine & just shake it by hand like a pollen or wikka box after the drum is finished running.