I bought a cheap bedframe that started sagging in the middle of the top and bottom main support bars after a few months of use. As usual for this sort of thing there isn't a great warranty policy, but I also didn't want to buy a new bed. Weirdly enough the smaller supports throughout the main body of the bed were fine.

Now I'm no engineer, but I looked at this puppy after a few minutes in fusion and thought... yeah that'll hold. Anybody with more experience feel free to remix this and optimize the amount of plastic used, but as is I got it down to about 100 grams, and it has been holding strong for the past week.

It's a pretty simple design. I went with a cone because I thought that shape would maximise strength per material used, and there is a dome in the interior to distribute weight as evenly as possible.

Those main support bars at the head and foot of the bed I mentioned are both square with a bolt through the center. so I measured out a slot to hold it. They aren't really precise to my frame. I left a little wiggle room, but i've moved the bed while cleaning the room and the support held on without issue.

Anyhow this is pretty custom for my use, but it might be a good jumping off point if somebody else feels the need to reinforce their bed frame or any other piece of cheap furniture that you just aren't ready to get rid of yet.