The first idea when making these were to store round pipe, hence the hook up so it would not roll off.

I also have many hollow channels so it prints many solid areas, making print very strong, Mine are printed in ABS or ASA and I can fill with metal pipe no issues.

Also there are holes that are thru the print left to right so I could add hardware to hold the layers together in case of any issues with layer strength

There are a couple different thickness use as you see fit.