baby block tutorial. easy enough to find a plastic bag that makes the right kind of noise for what you're going for (usually thicker plastic works better) and then just add that to the back of one (or more) of your little squares. i make flat crinkle toys for relatives and incorporate crinkly portions to various items i make for my own family and the thicker plastic works pretty well!
Baby Blocks Tutorial | Sew Like My Mom (If you want to put letters or numbers on the blocks, but don't have the time to hand sew, you can also iron them on with fusible webbing or a similar method. ~ Melisa)