Update: Now with heatsert option using standard Voron heatserts.

This design uses 3 x 40mm fans to keep the stepper drivers on Octopus boards running nice and cool. Confirmed fit on both Octopus 1.1 and Octopus Pro. Tested for clearance ONLY with BTT TMC2209 drivers and heatsinks; other brands may have slight height differences. The default bracket has a 26mm clearance from the face of the Octopus board. Measure your setup to make sure that from the face of the board to the top of the driver heatsink does not surpass 26mm. 

I will gladly modify the height upon request. Please let me know the desired height and what steppers you are using to make it easier for future makers.

Bolt size for fans will depend on fan height. For Noctua 40x20mm fans, 12ea M3x25mm (SHCS) bolts are perfect. 12ea M3 Nuts are used to secure the fans. I usually like to use heatserts but I have too many M3 nuts. I'll make a heatsert version if I get the request.

Bolt sizes for the bracket are going to depend on how the board is fastened at the bottom (i.e. din mounts). 2ea M3x35mm (SHCS) bolts should suffice for most uses.