The assembly instructions now read:
4 mounts for the Raspberry Pi: these are next to and above the GPIO connector. So, from the back of the PCB, put in the M2.5 nylon spacers. These will hold the Raspberry Pi. On the front of the PCB, secure the nylon spacers with the M2.5 nuts. Then, there are 4 small metal bolts (M2.5, 6mm long) which can be used to hold the Pi in place once you get to that stage.
I believe it should read:
4 mounts for the Raspberry Pi: these are next to and above the GPIO connector. So, from the back of the PCB, put in the M2.5 nylon spacers. These will hold the Raspberry Pi. On the front of the PCB, secure the nylon spacers with the 4 small metal bolts (M2.5, 8mm long). Then, there are 4 small metal M2.5 nuts which can be used to hold the Pi in place once you get to that stage.
This way the narrow part of the nylon spacers are what goes through the Pi itself, and on to the rear panel.