I thought I would share a couple of designs i came up with. I made this black one to fit printer paper held in place with magnets. It funnels the pellets to a little drop chamber with a door to remove the lead. I reuse the lead and make it into shot with a shot maker for reloading shotguns. The top has a little compartment that holds about an 100 extra targets. 
I made this green one to practice 75 yard shots, I used a long range gong for center fire that I had. I basically built the trap around it, put it on wheels with a handle to make it easy to move around. it catches the lead to reuse as well. I spray paint the background with white and made different stencils to layover and spray paint the targets. The shots show up really well, as you can see in the pic's (the dark spots), let me know what you think.
I made this green one to practice 75 yard shots, I used a long range gong for center fire that I had. I basically built the trap around it, put it on wheels with a handle to make it easy to move around. it catches the lead to reuse as well. I spray paint the background with white and made different stencils to layover and spray paint the targets. The shots show up really well, as you can see in the pic's (the dark spots), let me know what you think.
I'm guessing you don't have to worry about that.