They're little pouches filled with rice in a couple of different sizes/shapes to suit different applications. I made mine out of corduroy scraps. The trick is don't over-fill them with rice or they aren't able to be moulded into position around necklines etc.
This is how it's done:
- Cut some rectangles of various sizes;
- Sew them up on 3 sides [right sides together]
- Turn them right way out & fill with rice [not too full]
- Fold raw edges inside pouch & machine stitch closed so no rice falls out