Here is a quick demonstration of how (not) to make a high jump bar using only a pallet and a couple of clips.
(it should be finished processing soon.)
Its maximum height is 1.2m and it is also 1.2 wide unless you find a longer bar to use. Sometimes the clips have to be angled a bit so that the bar doesn’t fall over.
Just as I had finished making the bar I realised that I had got things a bit wrong, but if you think about it you should be able to do a better job than me.