I was at the upholstery store the other day with my girlfriend and happened upon a 24x24x24 block of green foam. It was labeled "ottoman foam" and was fairly dense. Not nearly as hard as a target you would find at your local sporting goods store but at $30 it is far less expensive. It was sturdy enough to sit on and only sink down a bit, but the question I am asking is if it would be dense enough to stop and 300fps arrow and if so how long would the foam eventually last? If anybody has experience with materials like this or has tried it for themselves I would love to hear about it.