Depends on what stresses it's subjected to. I needed to suspend a TV monitor from the ceiling, and although wall mounting kits are readily available and cheap, ceiling mounting ones aren't, and are desperately expensive from pro suppliers - almost as much as the monitor. I made one out of 15mm tube, using end feed fittings where needed, and not only does it look very good, but it's well up to taking several times the weight. Total cost under 20 quid.