I have a CWWK Mini Fanless PC running OPNsense firewall. It gets a little warmer than I'd like with no fan, so I designed this mount to hold a fan on top of the heat sink case. The case supports an 80x10mm fan on the bottom, but the CPU is on the top side of the board and directly attached to the heat sink/fins. Placing a fan on top has reduced idle temperatures from ~45c to ~30c and 100% load temps from ~60c to ~40c.

This should fit any standard size 120mm PC fan. The firewall has micro 4 pin fan headers. I used https://www.amazon.com/dp/B09DYLY95R?th=1, cut the normal 4 pin PWM connector off, and soldered the micro connector on. Pinout on my mini pc's header was the same order as normal pwm headers, which means on this plug (unfortunately) red = common/ground, black = 12v. Either remove the punch out on the bottom and make a big hole, or what I did is slice through the mesh covering the vent holes. The micro connector will fit in the slot with a little bit of encouragement.

I originally printed this in PLA, which worked fine, but the pins that go through the fan were easy to snap off. I re-printed in PETG and it seems much more durable. I used PLA for the support interface on the PETG print and the supports pulled off extremely easily, while leaving a flawless overhang. Make sure if you do this, you do sufficient flushing between materials.

My print profile settings are just what I used to optimize the print quality. Should work fine with standard/default settings. I didn't even use supports with the PLA print and it still turned out decent.

To install, just put the fan in the holder and slide into the PC from the front or back. It should be somewhat snug.

Feedback welcome, this is my first original design for a functional print.