While making a DiY chiller for the laser engraver, I have got a need to straighten radiator-condenser aluminium fins. Mine are spaced at 2.8mm one from another.
Here the first photo is of the 12 tooth version (the initial design) which I have advanced by cutting off 6 side teeth. I have noticed that 6 tooth version is much easier to use and allowed me to press teeth together while straightening. Also it is much easier to place teeth between fins of the radiator. ( you can see me using that "trimmed" version in another photo). Therefore I have adjusted the design for thingiverse.
Have printed that in HIPS as this material provides more accurate dimensions when printed.