This can hold 4 Dell Optiplex Micros (Designed specifically with the 3000 series in mind; however, the 7000 series should work too.)
You MUST pull the rubber pads off of the Dell Optiplex or it won't fit.
If you print plate 2, it has a slot for the switch flex mini from Ubiquiti as well.
No additional hardware is required, everything should just slide in.