Comment by Animats

> Now you need to remember this is not a metal panel it is a 1.6mm thick fibre-glass one, it does the job, but it wont take much abuse like a metal one will and flexes a little when handling it.

That's when you design in a PC board stiffener. These are just pieces of metal, U-channel, L-channel, or solid bar, to add some structural strength. Cheap and easy, but rarely seen in hobbyist work. Any board with buttons or knobs or connectors unsupported for more than a few inches should have some stiffening. You have to allow space for stiffening bars when designing the board, and you need to place screw holes.