Outer Limits 4x4 Board

Putting a thermofan on, got some 2.5mm ally plate as little brackets to go on the thermofan.

Only thing is, what is the best way to secure them to the thermofan, I'm worried about anything poking out the other side taking out fins.

Only thing I can think of is countersinking... but it doesn't really seem thick enough for it.

Zip ties. Blue ones are the best...

Some thermos come with the fitting ties. If not you should be able to get them at your local sprints etc.
Good Luck with that. I have always found the factory clutch fan to work great.