My Air Blower fan has broken, I couldn't find the exact size replacement nearby hardware store, I needed it ASAP, so 3d Printing to the rescue, 10 minutes on Fusion 360 and 9 Hr of printing and I got a very well working Replacement fan.

I made it on CF-ABS on my Qidi X-Max but I thing PLA will also work well.

My fan was 100 mm diameter. I have also attached f3d file so you can change the values according to your need.