No, this is not about sticking the Arduino where the people at certain other fora would like to stick it, but what I do to mine.
My worktable is a mess. The only free space is a palm sized area that I need to move the computer mouse. There are plenty of conductive object, and I really do not want to short circuit The Arduino.
I have two solutions that I use.
The first one is a “specimen box” that we use at work for whatever need to be put in a box. It is clear polystyrene, and relatively sturdy. The board just fits in it, and cutting a square hole for the USB and a round one for the plug has it sitting nice and cosy, and well protected from most things on the table.
There is still room in the box for other components.
Solution two is a piece of 5mm plexiglass with a breadboard, a 25A solid state relay and three sets of holes, allowing the Arduino to be mounted with nylon screws in three different directions… It is still in the direction where I first mounted it. The flexibility seemed like a great idea, I just never used it.