I set this up out back for my daughter (she's 7). The party line is that it is target practive for her marshmallow gun. Since my understanding is that the device she uses to shoot her acorns is illegal in Massachusetts.
It's out behind the pond, by the brush pile, in front of the brook. The other side of the brook is conservation land. It's not visible from the road - which is good. We live in a bit of an upscale town (million dollar homes are the norm here, not the exception) so most people do not tend to make target ranges in their back yard.
The targets were made out of an old rimmed baking sheet, a metal plate, an old pot lid, and a tin can. I spray painted them, and then used some spare paint to hand paint the numbers.