My 2004 RX-8's climate control fan knob broke right on its stem. Cost of a new one is like fifty bucks! Gluing it back together is difficult because of the small surfaces and the fact that it's HDPE. So I made this little adapter that uses a friction fit on the remaining bits to re-create the necessary mounting hardware. It may fit other years, not sure.
Here's an attempt at a step-by-step. Watch my YouTube video to get a slightly better idea of what's going on: http://youtu.be/Ira08ukeK8A
You need to clean up the remaining bits of the knob's stem (or stalk, whatever you wanna call it). Look down the D-shaft. You'll notice a small X inside the D-shaft. Trim the D-shaft down flush with that X.
Print this out. I used 0.4 wall, 0.4 top/bottom, external supports, and 15% infill on Cura. I'd recommend using 0.6 wall/top/bottom if I were to re-print this; my print has gaps in the top layer as you can see.
Go to your car. Push the print onto the shaft.
Line up the knob and push it onto the print.
Enjoy your newfound control over the fan!
The author marked this model as their own original creation. Imported from Thingiverse.