It's not terribly difficult to make your own little Alexa-powered voice assistant with a Raspberry Pi, but one caveat is that you have to push a button before you can initiate voice commands. The Raspberry Pi Guy came up with an elegant solution using a Sense Hat.
The project itself is no different than other DIY Amazon Echo's. First, you'll need a microphone and an external speaker, then you just need to run a few simple commands. What makes this one different is the addition of the Sense HAT instead of just a boring old button. A Sense HAT isn't a cheap solution at around $50, but it's definitely one of the cooler ones, especially considering the little animation system The Raspberry Pi Guy worked into this one. Head over to GitHub for the full set up guide.
Artificial Intelligence Pi [GitHub via Adafruit]