If you buy sand that is specifically sold for use in childrens' sandboxes, it is already treated to make it safe. However, I think the last time I bought it, the smallest size was a 10 lb. bag. You can make an awful lot of pincushions with 10 lbs. of sand! I purchased a bag of crushed walnut shells from one of the chain pet stores. It will still make more pincushions than I could want, but it was a smaller bag and reasonably priced.