We tried making ice cream the other day. My plan had been to follow the basic "ice cream in a bag" recipe: half and half, vanilla, sugar in the inside ziploc bag, ice and salt in the outer ziploc bag, and shake. We didn't have any ziploc bags, so we found plastic containers to use instead. I don't know if it was the hard plastic or the fact we definitely did not have enough ice, but the ice cream did not become ice cream. We sipped them, trying to pretend they were just very watery milkshakes, but it just didn't cut it.