Did you leave the garage door open? No really, did you?
If you find yourself asking this question–rationally or not–over and over, then this notifier kit from ThinkLearnDo is a perfect solution. The kit takes the form of a NodeMCU carrier PCB, which activates the system when the door is open, and sends you an email after 5 minutes if it’s not closed.
The device is cleverly designed to attach to the door itself, with a tilt switch angled at 45º. This switch applies power to the NodeMCU — a wildly popular breakout board for the ESP8266 microcontroller — when the garage is in an open position, allowing it to boot up when needed, without actively powering the sensor itself.
The device does not include the NodeMCU itself, and you’ll need to program it per documentation found on GitHub. This documentation also includes a 3D-printable case for the device, or if you so prefer, the version listed here includes a nice enclosure to protect your components.
On the other hand, if you’re looking for a way to actually control your garage, a Bluetooth/relay-based controller could be a good solution!