120mm Fan Duct for Mikrotik CRS305 10G Switch

This is a fan duct to fit a 120mm fan to the underside of a Mikrotik CRS305 10G switch, for extra, quiet cooling of the processor and SFP modules. It attaches to the switch by sliding a pair of lugs into the switch's wall mount screw slots, with a couple of spring tabs to hook over the back side of the switch so it can't slide out. The duct divides the fan's airflow partly into the processor area and vent holes, and partly onto the SFP modules directly, where the duct extends past the front of the switch. My switch processor temperature dropped by around 25 degrees C, and my 10GBe SFP+ module feels cooler to the touch, but it lacks a temperature sensor.

The fan attaches with two or four #8x1-¼" sheet metal screws (metric equivalent: m4.2x32mm,) and will require external power (unless you want to mod your switch.)

The model has some moderate overhang angles on the corners, so I printed with PLA, which should be fine since the switch doesn't get all that hot even without a fan. There are a couple spots which require supports (included in the 3mf file,) and the model was optimized for a 0.6mm nozzle, but Prusa Slicer v2.5+ should have no problem making it work with a 0.4mm nozzle. The mount lugs may require some shaving to get a good fit, and definitely make sure to clean off all support material.