This is one of those well-it's-sort-of-a-tool posts.
I like to keep my rifle skills honed using an upscale pellet rifle in the backyard. Not too much noise to scare the neighbors and ammunition and the CO2 to propel it is cheap. To avoid pellets ricocheting and littering the lawn, I needed a pellet trap. The result is shown in the first photo.
I bought a small wooden crate at the local crafts store and fitted it with a handle surplussed from some electronic rack gear. The bottom of the crate is lined with duct seal...
This stuff has a consistency like very dense, very sticky modeling clay; it never hardens. A .22 pellet fired point blank into it will be stopped and trapped (i.e., no ricochet) in less than 3/8" penetration. With a layer in the crate about an inch thick, every pellet gets trapped, even if the surface is chewed up by previous shots. The "ballistic putty" sold by airgun suppliers for pellet trap use looks suspiciously like duct seal but sells for a lot more.
The crate is further enhanced by strips of plumber's metal tape applied at the top and bottom edge. This allows me to use the white magnets shown to secure paper targets.
Paper targets are fine and all, but it's fun to shoot stuff that shatters as well. Fortunately, Necco wafers can be had cheaply in the dollar store. They shatter impressively and the fragments are devoured by the lawn fauna (better them than me) or they dissolve when the sprinklers come on. I glued four miniature clothes pins to a block of wood. Set this in the pellet trap and blaze away.