I've seen a shotgun rail that was like 4 inches wide, with HDPE thrown over the top. you could do that if you wanted a real skinny box/bar rail, or you could just man up and leave it shotty
How thick is the HDPE? I have a rail made out of 4x4's so I got 1/8" HDPE (a little too thin). Well 4x4's and 2x4's aren't actually 4 inches wide so it hangs over and sucks. I would do it with 1/4" thick HDPE though. Just make sure it isn't hanging over the edges of the wood.
hey thats what i have 1/4" hdpe so it works on my other box fine. but in just worried if i make a skinny box/bar that when spinning off that my edges will cut into it alot.