So speaking of benches, this is cool:

Plastic Recycling of Iowa Falls, Inc. produces benches made from recycled plastic bags.
The benches are durable, do not require painting, and the “boards” don’t warp or splinter.
You might be surprised to learn that it takes 10,680 plastic shopping bags to make a single bench, but the more plastic bags it eats up, the better.
In addition to making seven variants of benches, PRIF also makes picnic tables, planters and trash receptacles, all of the same material, which is 96% plastic bags and 4% coloring additive to make it look like wood. They even sell a wide variety of dimensional “lumber”—2×4s, 4×4s, 3×10s, 6×8s, you name it—that can be cut, drilled and nailed like the real stuff, with the added bonus that you’ll never have to paint or reseal the deck/structure/staircase you make out of it.

More: Plastic Recycling of Iowa Falls, Inc.: Using Plastic Bags as a Raw Material Since 1984 – Core77