We made two different bullet traps for my shooting range here at the house. I have the ability to shoot out to 200yds. I built a double wide bench for rt & left hand shooters also.
The first trap I made, I used 3/8" plate steel and cut it into triangle shaped pieces @ 24" at the bottom of the triangle and @ 24" to the point of the triangles.
I assembled them in a pyramid shape and welded the seams inside and out. I got a piece of 1" thick plate steel 6" wide and 12" long.
I cut the pointed end of the pyramid off at the point where the 6" wide piece fit into it, basicly so the pyramid had a 6" x 6" opening in the top instead of a point. I welded the 1" thick plate to three sides (top & sides) leaving one side(bottom) unwelded, I them cut an additional 1" out to the bottom panel so the bullets had a place to fall out after hitting the 1" thick plate. I mounted a coffee can to catch the bullets.
I welded some legs to it and it was done.
We move it around the range pending on the yardage we are shooting.
The second one was a little simpler, just a 24" x 24" sq. plate of 3/4" thick steel with 4 legs welded so the plate was at a 45 deg angle to deflect the bullets into the ground.
I use old reality sign frames with scrap plywood in them the hold the targets and place the traps behind them to stop the bullets.
We shoot some big caliber stuff into them. The only problem I ever had was with a .30-06 with 180 gr round nose bullets, shot holes straight through the side flange of the cone trap at the outer edge.
Both ring like a church bell when hit though................
Maybe this will give you an idea for one of your own.
FDXX75