I made one for my Aspberger's grandson. After some trial and error, I used styrene beads for one and pea gravel for his brother's (who HAD to have a matching one) and invented an easy way to make it. I won't bother to describe it now but it takes two soft beach towels, some muslin (or leftover fabric of any quilty kind) and some easy sewing. I'll write up the directions if anybody needs them; just PM me.