This was a father/son project that spanned several weekends, and we hope you like it.

This is a modular design which helps with printability, covers the screw holes, and allows for faster iterations.
I thought of making a phone slot but haven't gotten around to it and that is now available for the original version.

This should work for the NG 9-3 models, anything with the 2003-2010 interior.
If you need right hand drive, just mirror/reflect both parts in the slicer.

Printed at 0.2mm Quality with 30% cubic-subdivision infill, but .3 and 25% works fine. If you want a texture, try the fuzzy setting.

You will need some supports, though the design is meant to minimize them.
I use tree supports in Cura.

The two pieces take about 16 hours to print on my stock Ender3 v2. The modular joints are slip-fit and need to be tight but not too tight. They have 0.3 mm clearance all around. Consider this when choosing print quality.

Enjoy.

UPDATE 07.11.2024:
In a long overdue revision after some critical community feedback, I have added the demanded chamfer to the design.

I am keeping the original as an "easy print" version, and adding the new as the '2.6' version. The square parts are not going to line up with the rounded parts, so ensure you are printing '2.6' files.
This also necessitated a new cup design. The cup moved slightly, and I also added a matching blank module with chamfer for anyone wishing to create their own modules.. Just show us when you do!
Cheers