This is a holder for the LJ18A3-8-Z/BY inductive sensor, which is mounted directly behind the fan, so it's verry strong. Also available for sensor LJ12A3-4-Z/BY (http://www.thingiverse.com/thing:1429335 )
Best way to print this part is straid up. This gives the best result, but you have to use support.
This part is designed with Cubify Design