Personal
Adding AUX Input to My Car
My current car is a 2005 Honda CR-V. It was in beautiful condition until a hail storm last year turned it into a golf ball. I’ve got a cool MiniDisc deck installed, which pumps out some great sound, but making new mix discs all the time is a bit of a chore, so I also have a 3.5mm headphone cable that I plug into my phone to get tunes for traveling.
At least, I did, until I finally had to update my phone, and of course it doesn’t have a headphone port anymore. Thanks for nothing, modern world.
And so I put a Bluetooth adaptor in there, that puts out stereo sound via a 3.5mm jack. For a number of reasons I wanted to change the overall configuration and I decided a headphone jack AUX input was required. I briefly considered drilling a small hole in the dash, but I prefer to avoid this sort of thing if I can. I noticed a blank button in the dash, down low near the cigarette lighter socket which is now basically a permanent USB power output. And since UGreen makes a nice little USB to 3.5mm Bluetooth receiver, my course was set.
I had to buy three parts: a 3.5mm socket, and two RCA connectors. After that it was time to spend a day modeling and printing a new thing.
I popped the blank button out, measured it up, and did some sketches.
It was a surprisingly easy design process. The driver-facing panel took only a handful of revisions, one to match the rounded corners, another to get the depth of the clasp right, and the rest to accommodate the key ridge at the top of the hole.
I didn’t want a socket that would have the incoming cable sticking 90° out of the dash, so I went with a partially recessed, tilted receiving socket that would allow the headphone cable to lay flush.
Testing the fit of the socket in the panel
It turns out that red matte PLA has terrible layer adhesion and it would snap rather than flex. This is something I learn several times every year. I use “learn” a little bit inaccurately here.
These are the parts I created for this assembly
I went with a layered assembly, using two M3 screws and inserts. The RCA panel is as close as it can possibly be, to reduce the risk of the cables running into anything in the dash. Even so, I had to carve out a hole in the retaining bracket that holds the 3.5mm socket in place. The only way to make this any smaller would be to start cutting down the RCA connectors.
This assembly just pushes into the hole in the dash
And here it is, the final result. It works perfectly. 3D printed parts are not a great choice for flexible clasps and despite testing fine, the two clasps on the side cracked off and fell into the footwell the instant the assembly was jammed into the dash panel. But it’s such a great fit that it’s in no danger of falling out. If it comes to that I’ll find another way to hold it in place.
I am super pleased.
--NFG
[ Sep 25 2026 ]
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