My feeder isn't 100% waste-free, but it seems to work fairly well at reducing waste. It's a plastic bucket with a lid, sitting upright on (screwed to) a slightly broader lid with a lip on it, which is the tray they eat off. I have drilled a series of holes around the very bottom of the bucket, just large enough for beaks and large kernels of feed. Inside the bucket is a cardboard cone that directs the feed toward the edges and the holes, away from the unreachable middle. There isn't much poo problem with the feed tray, either, even though the lid is flat: they like to sit on the lid handle, and their bums don't reach over the edge. You could put a conical lid on to keep them from roosting on it altogether. The whole feeder assembly is sitting on stacked bricks to keep it well above the level of the bedding.
I think the buckets and lids were from restaurant-size tubs for margarine, soup stock, mayo, etc. You could probably work this idea with those oh-so-common plastic 5-gallon pails, as well.
