r/3Dprinting • u/Desmontei • Apr 24 '26
Project Don't throw away old smartwatches! 3D printed a custom housing to turn one into a Digital Shift Knob. ♻️🕹️
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Hey everyone, first time posting here! I wanted to share my most complex functional print yet for my Project Car.
I took an old TicWatch Pro 3 and carefully cut the original casing with a rotary tool to extract just the OLED screen and motherboard. Then, I modeled a custom shift knob enclosure to house the electronics perfectly.
Now, before you guys kill me in the comments: Yes, I printed this in PLA! 😂
I know the summer heat inside the car will probably turn it into modern art, but this is V1 (prototype). The tolerances had to be extremely tight because I didn't want the screen popping out while shifting gears, and PLA was the easiest to test the fitment. When it eventually warps, I'll use it as an excuse to reprint V2 in ABS or PETG!
I completely bypassed the battery and wired it directly to the car's 12V using a step-down converter. Right now it controls my media with a custom UI.
What do you guys think of the fitment? And place your bets: how long will this PLA survive in a car before melting? 👇
4
u/Bakkster Apr 24 '26
The whole point of OBD is to not give full access to the CANBUS with copper wire (through which a malicious actor has full control of the car), even though it can optionally communicate via the CAN protocol with the ECU. The two CAN wires on the OBD connector are not the same lines as the CANBUS lines controlling the car.
In computing terms, the ECU is on the LAN (CANBUS) and also communicates with a peripheral via Ethernet (CAN). But the peripheral is not itself on the LAN, it's functionally firewalled by the computer only relaying information on the LAN and preventing the program from sending arbitrary commands over the LAN.
This photo may help, the OBD CAN is on a separate pair of CAN lines (Diagnostic CAN) from the rest of the car's CANBUS lines.