I've seen this stuff on a friend's deck...looks pretty good though it's over wood, not composite. It's very thick and textured. Comes in 4x and 10x (I think). 4 times and 10 times thicker than paint...yeah, just like truck bed liner.

http://www.homedepot.com/p/Rust-Oleu...1100/204748612

Covers up a lot of sins.