Nest has been in the news all week following Google's announcement that it would pay $3.2 billion in cash to purchase the company. That purchase validated Nest as a viable company in many people's eyes, despite the fact that it makes rather expensive alternatives to devices that are already in your home. Of course, not everyone wants to pay $249 for a thermostat or $129 for a smoke detector. In light of that, the team over at Spark set out to build a connected thermostat using open source components for under $100.

Spending a total of about $70 and 15 hours, the team of four more or less accomplished that goal — they built a thermostat that can connect to a Wi-Fi network and be controlled by a simple webapp. The final product is made of acrylic and wood and looks a lot like the Nest Learning Thermostat, but doesn't quite match the capabilities of the real thing. It doesn't have the pretty graphical interface of the Nest or the slick smartphone apps. But it's round, has a basic LED display, can detect when you are home or away, and can be controlled by twisting its ring, much like the Nest.

The Spark team has published their design and related schematics on Github, so you can build a connected thermostat yourself. You can also read their story and get more details on each step of the process on their blog. Chances are, this device won't get you a $3.2 billion payday like Nest, but it looks like a fun little project for those willing to dive in.