Power supply holder(tricky to configure)

Holds a power supply (or a similar shaped box) to a wall. Obviously you *dont*
want it to fall! Make sure it is secure!(your safety is your responsibility)

You'll have to fit it to your situation. Which is why i havent provided the
`.stl`. To be honest, this is quite involved.

`pl`, `pt` are the plank length and width respectively.

If it is a general box, `psl`, is the length. `pshf` and `pshb` are the height
front and back, not 100% if that works you could just set them the same