Here is a bit more background on how he made this device:

54 chosen as this fits the hexagonal close pack layout. 6 more could be added in the centre. 18 in props at 5000 rpm though hazardous, are still much less so than 6, 5 ft ones. Where could you get a low power 5ft prop from weighing less than 1Kg with opposite pitches? The 54 gives good redundancy as mechanical and power electronic systems are the main failure areas. I have had one ESC randomly fail already. Controls could be made fully redundant (9 x KK2.15s) so only the control sticks (and pilot) are single failure points. Redundancy increases the likely hood of failure but reduces the consequences.

This is pretty cool and impressive that he could make this. Congrats on the accomplishment!