RX-8 Fan Control Knob
The climate control knobs on Mazda's RX-8 are notoriously delicate. This is a much more robust version of the fan control knob. Use the metal D sleeve from your original knob and push it into the hole into the bottom of the post of this knob.
UPDATED: Has a window for the dash lights to show through so you can see the setting at night.
Find the temperature knob here:
http://www.thingiverse.com/thing:73813