So you're saying a box of rags

[JoeW]

does the trick for a pellet trap...sold. Just one question. What do you do when you start accumulating shots that result in larger holes in the side of the box facing you (that you are hanging the targets over)? I haven't done it yet, obviously, but would think the rags or whatever your fill material is would start popping out through those holes. Do you add a new cardboard face and tape that on? Or just tape over the holes? (Thanks in advance for your patience. I know this has been covered here and elsewhere ad nauseam. I just haven't seen my specific question addressed in a way that makes sense to me.)

[ChipEck]

When the hole in the box grows I staple part of a cereal box over the hole. That way I get nice round holes in my targets.

Chip

[dronning]

When the hope in the box grows I staple part of a cereal box over the hole. That way I get nice round holes in my targets.

Chip

+1 on cereal box I use the to repair the backer for bullseye matches too.

[Rover]

You put the box in a slightly larger box with most of the face cut away so that you're still shooting at a target on the smaller box. When the lint and target scraps fall out of the smaller box they will drop into the larger box.