I built a compost screener using 1x4s and hardware cloth. I used 1/4 inch hardware cloth, but I'll probably replace that with 1/2 inch hardware cloth at some point. I basically just made a frame with the wood that was about the size of my wheelbarrow and stapled the hardware cloth to the wood frame.

Originally, I thought I'd sift into the wheelbarrow and use it from there, but I've just been sifting directly on the ground.

You could use 1/4 inch mesh hardware cloth, a bit more difficult because less material goes through easily, or you can use 1/2 inch mesh hardware cloth which will let through bigger bits and pieces of your compost.