Step 1: Supplies
The hardest part was figuring out what light to use - initially we thought we would just drop a wire through the pipe and make our own light, but due to cost and the fact that we have never fused/made lights from scratch, we just found lights that we took apart.
Remember to make sure all the parts fit together - we found that we could pop off the clip to the light and easily screw in the light to the 3/8" coupling. Hence, everything is based off this diameter, but if you want a thicker pipe, you can easily find couplings that go from one size to another.
And we used gas pipe (black) because it was slightly cheaper - the steel costs the most.
Technically, here is what we used, and again, the diameter was 3/8".
4x- 4" pipe
4x - flange
4x - 90 degree elbow
4x - 3/8" going to 3/8" coupling
4x- screw and washer (short enough that it will not go through the wood shelf)
4x - lights