Old rags and clothes is all I used in the 80's before I had money for targets. They would stop any field point with no issue and do it forever. The only trouble was if you left it in the rain. I never used a box but used old feed sacks like @JC3.
Another great target but not real practical is using flattened cardboard boxes. I took the old cardboard boxes that I got from stocking Piggly Wiggles shelves at night. I stacked them horizontally on a pallet until it was about 4 foot high and ratchet it down. That thing lasted forever, with tin over it.
Heck, I may do both of those type targets again.
Another material that you can use, instead of cardboard boxes, is carpet padding from a rip-out. My buddy does flooring... take (2) 2'x3' pieces of 3/4" plywood (one top and one bottom) and layer the padding until you reach your preferred height. We used ratchet straps or threaded rods to tighten everything down. Maybe not the easiest to pull arrows out of, but...