It can be useful to set the Pro Micro in boot loader mode to upload new firmware. This is done by connecting the Reset pin to ground. To simplify this a push button can be connected to RST and GND on each Pro Micro.
First verify how to connect the push buttons. The ones in the parts list connects the two pins one each end of the two lines.
If you bend the two unused legs a bit towards the middle, they will rest against the PCB. Use the diod legs to extend the push button legs directly to the Pro Micro. Since the Pro Micros are mounted different ways the two push buttons both will face right, see the images.
Right Hand
Left Hand (before the diod legs have been trimmed)
Right Hand in profile
