Compressed cardboard works well, but it takes a lot to make a target and it has some weight. Canned foam works well for a few shots, but wears quickly and it takes several cans to fill a gunny sack. Carpet works well, but as stated... heavy. Bead board from home depot works well. you can buy a 4x8 sheet and glue it together. You gotta use glue made for foam. Any petroleum product glue will melt the bead board. The Blue foam works well, denser than the bead board, but leaves a residue on the arrow that has to be scraped off. The best inexpensive target I have found is a gunny sack filled with visqueen (plastic). Stuff it as full as you can, stitch the end closed and you are good to go. Very light and lasts a long time. If you have access to a lot of plastic, then the cost of the sack is $.75 to $1.50 each. You can get them at farmers feed stores. Visit a construction site and pickup the discarded plastic they might have laying around. They will likely give it to you just to get it off site when they are finished with it.