It can be any material and any size. It is best to tuck the toys into the center - nothing falls out that way. The button and loop are only a precaution. Even a bath towel works but something to match up with the toy would be helpful. Now days there are fabrics with all kinds that could be quilted or appliqued into the mix. I did not use batting in the one I made but it might even things out a bit to have something in the middle - then again just a plain hemmed fabric might be just the ticket.