We wanted to take our bikes camping with us, but needed a means to transport them and the camper and all of our gear at the same time. (Meaning, we needed a bike rack that could be mounted on top of our pop-up camper.)
I was determined to not spend any money. So using stuff I scrounged from the garage, I came up with this. (Yes, those are old table legs.) I drilled holes in a few rough cut poplar scraps, stuck PVC through them, put some scrap strapping across the front and back, and then installed the uprights and spray painted it black with surplus paint.
I needed it to be light enough to be able to easily put on and take off of the camper.
It also had to be quick to build, I only had a couple of hours.