I found a great little target that has an unlimited supply, never needs to be policed up and cost next to nothing. I use ice cubes, you can get trayes for different sizes and if you want different colors just ust some cheap food coloring. They really don't need to be for rimfires, you can make any size you have containers for. My wife is always hollering at me for using some of her dishes to freeze ice in. I like the fact that you never have to spend time gathering them up like you do cans or plastic bottles, the sun takes care of all that for me !!