Picture of Safety backstop for a pellet rifle’s pellet trap
Level concrete blocks 4 ways.JPG
Bottom pallet on concrete blocks.JPG
Supplies needed -  
Three - wood pallets (strip the top and bottom (skid) slats from one and reserve )
Nine  -  5/8 in. x 5-1/2 in. x 6 ft. wood fence pickets
Four - concrete blocks for a base
One – ribbed black plastic carpet runner (2 ft. x 6 ft)
One – ¼ in x 4 ft x 6 ft. rubber mat
Four  - bags of rubber tire mulch
Six -  dense fiberglass insulation boards (about 2 in. x 18 in. x 18 in., wrapped double in wood pellet        bags)
Box of ceiling tile staples
Box of 1-1/4 in. exterior Phillips wood screws
Lots of scrap bricks, concrete border, and concrete blocks (counter balance and safety backstop)
3/16 in. nylon cord and a roll of duct tape

Tools needed – 
Electric drill
Staple gun
4 ft long level rule
Saber saw

Instructions  –  
Remove the top and bottom slats from one of the pallets, remove all nails, etc. 
Measure the outside edges of the pallet that you’ll use for the bottom, front to back and side to side.
Align the concrete blocks outside edges to those measurements and level them four ways (side to side, front to back, and to the other three blocks.