Thanks so much for the design! It works great on my printer. For anyone out there that is having trouble wiring. Wire your main cooling fan to your PCB board in your printer. Coming from the switch there are thicker gauge wires. Underneath there are some DC leads to solder your wires to. The fan will take the appropriate current it needs so there is no need to worry about frying the fan. As for the part fan, I spliced two separate wires going to parallel to the original cooling fan wire. Even with all three fans hooked up to my printer (extruder cooling fan, 2 part cooling fans) my printer is able to run them all with ease.
I added a little hot-glue to the centrifugal fan to seal the part with the fan. I would recommend making a hot end sock so that you won't lose hot end temperature with so much airflow.
Lastly, in order to shut the part cooling fan completely off during a print, set the cura fan setting to 1% and NOT 0%. This will actually shut off the fan once the printer has started printing. Oh and I have a MP Mini V2 if you were wondering.