I was thinking about making my own as well! I haven't done any research but you'd need a smartphone dock, a good microphone/speaker (wireless microphones/speakers around the house?!?). Better yet, mount a tablet on the wall somewhere convenient/attractive (living room, next to thermostat, etc.) and wire everything behind it.
Change Android settings to always listen when screen is on, then keep screen always on (dims when not active). Voice-controlled App support galore! Google Now! Develop whatever you need/want!
The Echo is a neat idea put into action, but it can be hacked together in a much better way, very easily.
I've thought about doing it, but I don't already have the devices in my home that are capable of being automated and I've got enough money dumped into projects that required bits like this that I never finished as it is.
I would, however, be interested in trying to create a room simulator. I did work on living space automation for a while, a few years ago (specifically for hotels, not homes). One of the most difficult parts of designing good user experiences was the lack of ability to rapidly test, due to the need to setup a ton of devices, associate them together, maybe even flash them with new ROMs. You could get in two, maybe three tests as day, if you were really cooking. I wanted to be able to test as fast as I could compile code, you know, like I had gotten used to in every other software project I had ever worked on. But electrical engineers work with primitive tools and seem to like it.
Change Android settings to always listen when screen is on, then keep screen always on (dims when not active). Voice-controlled App support galore! Google Now! Develop whatever you need/want!
The Echo is a neat idea put into action, but it can be hacked together in a much better way, very easily.