I have four cories and Tango will gorge himself until he's sick on their pellets. I have Lee's two way breeder that floats in the tank. It's the 2nd one in Bettaxfishxcrazy's links.
It's pretty big when you take the divider out in the middle, maybe 5 inches long and 3 or 4 inches deep. You can take the grate out of the bottom even. I really recommend it. It just floats in the tank and the water flows in and out the sides so all you really have to do is put it in the tank, tip it on the side, lead your guy in with your finger (if he's anything like mine he'll follow thinking he'll be fed) and then tip it back up until the water drains from the two 'floats' in the sides. Then you just leave him drifting in it like he's on a little cruise.
I feed my guy in there so that he's more agreeable to the whole trick. I do this every day and he's fine with it. And the cories can eat without being molested and Tango doesn't make himself ill trying to swallow a pellet bigger then his head!
Here's pic so you can see how roomy it is once you remove the middle divider and the grate! I had to feed him anyway.
And here he is making a grump face at me... you can see the slats on the side where the water flows and the floats that hold it up. Please excuse the gross diatoms that won't leave my tank...