I order I spy squares from Ebay--a couple of packs at a time--saves me lotsa time buying and cutting. Very reasonable.
I make them for children -- 2 - 7 ish. That way they can learn to identify specific items - colors - numbers etc.
I take 4 - 5 inch squares, sew them together put a many colored kid fabric on the border and put it all together.
sometimes you can specify whether you want girl squares or boy squares.
Pat