Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:3903580.
This is a improved version of Roches E3D v6 Fan-mount for a 50mm fan. I have simply increased the length and curve of the clamp so that it reaches further around the heatsink and actually clamps on.
I found the original did not clamp and would simply fall off, so made this one, which fits nice and snug.
Printed with PETG, 30% infill, 0.2mm layer height.
[UPDATE 17/11/2019] New extended version. The space between the heatsink and the fan has been extended to improve airflow to the heatsink, the inner openings have been opened up more and clearances with Precision piezo Orion sensors has been improved. I have not tested this version yet, so please provide your feedback.