A DIY maker has repurposed an old smartwatch into a custom gear knob with an integrated display. Instead of letting the aging smartwatch collect dust, the project reuses its display, sensors, and processing hardware inside a 3D-printed gear shifter housing. The result is a unique modification that displays the vehicle's current gear position directly on the gear lever itself.
What I found particularly interesting is that the system doesn't rely on any direct connection to the vehicle's transmission. Instead, a custom Wear OS application uses the smartwatch's built-in accelerometer and gyroscope to estimate the shifter position and determine the active gear. This approach raises an immediate engineering question: how do you maintain accuracy when the vehicle is parked on an incline or driving through uneven terrain? According to the creator, early versions struggled with exactly that problem, occasionally misreporting gears on hills. The algorithm was later refined to compensate for these orientation changes, although a future version may incorporate an additional reference sensor for improved accuracy.
Beyond displaying gear information, the smartwatch also doubles as a media controller. Swipe gestures on the display can be used to control Spotify playback, adding a practical feature to what is otherwise a highly experimental build. While it may not be the most necessary automotive upgrade, the project is a good example of how older smart devices can be repurposed into custom embedded systems. The combination of 3D printing, onboard sensors, and a custom Wear OS application makes this less about the gear indicator itself and more about exploring unconventional ways to reuse consumer hardware.
