I have seen plywood used, but here at home I don't use anything.. My targets are hanging on a chain link fence, the other side of the fence is my camper

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Last night I was trying some new arrows I made and my In-laws popped by, her eyes got huge and says "what if you miss?"
I have missed the target in my early days of shooting, tore an arrow up going into my shop door on one, the second was when I was leveling my scope, put a broadhead through a $60 aluminum level..
Yes, a backstop is a good idea, plywood would help decelerate the arrow but probably wont stop it completely.