1/4 inch hardware cloth is not good enough? You can get that at a hardware store. You can construct a sieve with 1 X 4 inch lumber.

@Vladimir I have 1/8" and 1/4" sieves already, and for the particular task I am doing now I really need the 3/16" ~= mesh size #4. I think my time investment in creating my own sieve from scratch would make the item as expensive as just buying off the shelf products.