Do you have an old cellphone lying around somewhere? Don’t know what to do with it? Time to blow off that dust and convert the ‘dumb’ device into a smartwatch! This is exactly what Tinkernut has done. The DIY wearable not only tells time, but connects wirelessly to a smartphone over Bluetooth and notifies its user of incoming calls and messages via light and vibration.

The build itself uses an LCD screen and vibrating motor from a Nokia 1100 along with an Arduino Pro Mini to drive the system. A 3.7V 1100mAh rechargeable battery powers the gadget. All the electronics are soldered together to a perfboard, and housed inside a 3D-printed case.

Have an obsolete phone you’d love to repurpose into modern-day tech? Tinkernut has put together a detailed three-video series that explains everything from extracting the display, to getting it to work with the Arduino, to creating an app in the MIT App Inventor. Admittedly, this project kept things simple; however, there are plenty of other features you can add, including a pedometer to count steps or a real-time clock module so you can keep time without having the watch tethered to your mobile device.