Targets are fun no matter what they are made of, In my BB gun days I used to line up the clothespins on moms clothesline and had a regular shooting gallery. Sometimes they would spin and sometimes they would fly. She finally bought a big clothespin bag and filled it up because she got tired of running out of clothespins . We had a double line ,When I was running short on BBS I'd hang a tarp from the second line and recycle the BBs. When I was about that same age my Dad had a bunch of corn cobs in the basement to dry for seed , They took a beating once I figured out the kernels would fly when I hit them. I could do anything with a BB gun and all Dad would do is chuckle , I had a cool dad that way.
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In the summer put some pancake syrup on a piece of paper and try to shoot flies when they land and move . Fun stuff . I used to set my boys up at 50 ' with a 40x scope on a target rifle , Complete with a table with chairs and a score pad for bragging rights . That was my afternoon babysitter when 22lr were like 10 bucks a brick.