Here's a rack I made a couple years ago. It's made out of 3/4" sch40 PVC pipe and wood from PVC and aluminum pipe bundles. I drilled the holes in the 2x4's with a 1" wood paddle bit at an angle, the holes were a little snug by design. I hammered the PVC into the holes with a rubber dead blow hammer, the 2x4's had a groove on the back side for the plastic strap from bundling the PVC so I put a screw through the end of the pipe on the back side to keep them from ever coming out! This was just a quick rough project to help clean up the garage and it did its job!