This Arduino Mega attaches to a control box mounted near the front door that’s loaded up with an LCD, an NFC and RFID reader, and a few buttons to arm and disarm the system.

A new Instructables page has been created to make an eco-friendly DIY metal detector using an Arduino Mega just been combined with a 3.2 inch TFT LCD ...

You'll need an Arduino along with a bunch of various sensors to get the project rolling, and once it's all set up you'll have a simple, but cheap system to monitor your home.