QIDI Tech 1 Part Fan Controller

Unless you are printing only ABS you need this modification. It allows you to control the speed of the parts fan which significantly improves control over printed parts quality.
You need to print the box, squeeze into it the controller (might need to do a little filing) and wire it between the main board and the fan.
I purchased the controller from here:
https://www.aliexpress.com/item/DC-Motor-Speed-Control-PWM-Controller-6V-30V-5A-13KHz-Digital-Display/32843001132.html?spm=2114.13010708.0.0.3a994c4dSsIrpc
You need 4 M3x8mm screws for the box and 2 M3x15mm and 2 M3 nuts to attach it to the printer.
This thing was inspired by LEEPH postings in QIDI 3D forum on Facebook:
https://www.facebook.com/groups/1811744122380955/
Good luck! It works great for me.