This is a fan adapter that reduces from 92mm to 80mm and is only 5mm thick.
I wanted to install an 80mm PC fan in the rear of a pc case with provision for a 92mm fan, the adapter had to be as thin as possible. And since I only found adapters that apply very strongly (all with funnel / fan duct) I created my own.
This is actually already the whole story behind the adapter! :-D
Update - 2020-12-20 :
There has been a small update in which the print volume has been slightly reduced and also the hole spacing has been adjusted a little, see version 2. The changes are so minimal, that you can of course continue to use version 1.
PS: Also I have created an adapter from 120mm to 92mm in the meantime. :-)
The author marked this model as their own original creation. Imported from Thingiverse.