I use ground walnut shells. It's real finely ground I buy a 10 lb. bag at the pet supply store that is used for reptile cages. (About $10.00) I sometimes get it half price when they have it on sale. I make a liner for the inside of my pin cushions out of muslin and pack the ground shell in that then insert in the pin cushion. I made a bunch for a meet and greet last year. I do warn people they are filled with walnut shells, incase of nut allergies. Although people shouldn't put their pins in their mouths anytime, even after being in the pin cushions. This also has a little weight to it so I don't need to add anything else.