Neat idea! I made a firepit this summer out of left over bricks from our patio remodel. We ended up with a giant pile of sand behind the patio, which I leveled out, dug into, and put in our firepit (I'll redo next spring/summer with some rock base under it first, I think). Made two benches out of leftover 2x6s I had in the garage and some cinder blocks. Had to buy some pavers to do the retaining wall, but the rest was just made with scrap materials. I'm also building a rock path leading off the property using flat rocks that I pull out of the creek every time I go hunting out back. I am all about home improvement on the cheap