need auto feeder

[kien]

this is the most common one that I see at virtually every pet store.

http://www.marinedepot.com/NUTRAFIN_...FDFECF-vi.html

I don't use this one myself though. I found one that is more of a square than a ring but same principal (sorry can't find a link for this one). You can also MacGyver something by cutting out a hollow square or ring out of foam.