I replaced the factory Bose radio in my 2011 Miata SE and wanted to retain the aux jack. The factory jack has a proprietary connector on the back so I created this which has a 7mm hole where a standard 3.5mm panel mount stereo jack can fit. I made it in two parts for easy printing. There are registration nubs to help align it when gluing. I printed in ABS, smoothed the front with acetone and glued it together with CA glue.
Here's a link to the Fusion 360 file if you want to make your own version: http://a360.co/2zc0Ovd