Fan reduction 40mm to 20mm

I made this reduction for: https://www.thingiverse.com/thing:1615461 Reasons? 20mm fans is hard to find and it is more expensive than the 40mm one (at least on Aliexpress). I havent tried it yet and the model isnt best because it was made in Thingiverse so I look forward for some remixes adding for example connection between "circles" for better air float.

Note: You can edit Z height in slicer if you want to make it taller/shorter.