Geeetech Rostock 301 fan - improved

My second version of a cooling fan for the Geeetech Rostock 301.
Check my other design for more hints and tips. (https://www.thingiverse.com/thing:2253022)

I also made an adaptor to mount a 60mm fan. Not because I had too few cooling, but as a test... I want to go 60mm for the hotend itself, in an attempt to improve temperature break and retraction.
See https://www.thingiverse.com/thing:2700454.

22/Dec: added chamfer for bolt heads in upper part