Do you know what a Tangle Toy is? It is a really twisted toy… No, literally. It is an 18-link toy which you twist and fidget with to keep your hands busy. It is supposed to have a calming effect. It does, on me. But it could be better.
Quite simply, it feels calming to some people be able to twist something, but to smooth it out later. It means the problems can be solved. Things can get better. An object consisting of 18 90-degree angles cannot lie flat. The tangle can’t be smoothed out.
With 90-degree angles, you need a multitude of 4 to be able to lay them down flat: 4,8,12,16, etc. To make an figure with 2 axis of symmetry from pieces connected at 90-degree angles, you need 4 x (uneven number): 4,12,20, etc. I will photograph a broken tangle toy, to show how each time, there are just two links too few to actually make a pleasingly symmetrical shape.
In summary: A 20-link Tangle toy will be as twistable, but more un-twistable than one with 18 links. And the untwisting will give more peace of mind.