Some resources to help you getting started with STM32 programming.
The advantage of this support is that it inserts into hole from chassis underside. Nuts keep it in place and easy installation by hand without aid of any tool. Separator protects the PCB from touching the surface of the box. You can also secure the PCB to the box, by putting another screw from underneath the box into the separator bottom.
Note: Images are just for representational purpose.