I looked for something that made sense and didn't look like it was made out of my neighbors garbage, but couldn't find any. I ended up buying some. The info is in my DIY door thread, linked below.
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Overall "build thread"
http://wayalife.com/showthread.php?26097-I-guess-it-s-the-quot-Super-Stocker-quot-build
DIY trail/tube door build
http://wayalife.com/showthread.php?24449-My-DIY-Doors