Making your own SILENT pellet/BB trap

40 years ago I lived in a big ****ty and belonged to a pistol club to shoot anything I'd travel several miles in gruesome traffic, so I decided to shoot at home in the garage got me a couple airguns a rifle and I already had the pistol. i tried the cardboard box with carpet strips but it was not ideal.
I decided to build a genuine silent pellet trap. I built a box out of pine 12x12 x 10 inches deep the back of the box
is open and I placed a thick piece of plywood that was held with 4 screws so That I could get in the box to empty it
The front is also open to accommodate a regular clipboard. I carefully cut the clipboard to make an opening all the way round to be able to use card stock for targets, the clip holds the targets
for targets,. Went to a local electrical supply store and bought 12 pounds of Duct Seal,
( it's the putty that electricians use to seal big openings when they run conduit) At home I stuffed the DS into the box
to make about 4 inches thick it covered the entire inside of the box. I framed the front of the box with 1x4s to contain any pellets or BBs that bounced of the seal and drop in the bottom of the box, after gazillion pellets a few bounce on the ones in the seal. i have built several over the years always improving latest has a channel to insert the clipboard.