My girls just aren't into certain toys, etc. I thought the ball pit would be great because of their natural urge to forage, but nothing I did with it was acceptable to them...although they would quickly pick out any treats that were in there. After that they totally ignored it. Most toys, Euc, aren't very interesting to them either. I have a couple odd balls!
They like braided fleece vines that I hide treats in. Their bell balls. Strips of leather that are re-set on top of the cage each night because they spend a great deal of time pulling them all down, and stuffing as many as they can into their pouch. The plastic bracelets are only interesting to them if I tie one at each end of a leather strip and loop over a bar at the top of the cage. They'll pull one side into their pouch. It's always fun to see what they've been up to all night rearranging their 'stuff'.