Do you mean slanted side like a jersey barrier? But more of an aframe style with straight slants?
Like that kind of thing?
If that's what you're going for are you actually going to use the sides?
If you're just going to slide it front to end might as well just build a normal rail. If you want to hit it from multiple angles or drop in to the sides than go for it.
Wouldn't be very hard to build. Just frame it up out of 2x4s, slap some ply on there and through your pvc on top nice and snug.
Unless that isn't what you're building and then I have no idea.