Yes, I did both (the lego mindstorm one and the cubotino).
Cubotino is an awesome project, it's perfect to introduce robotics to kids (assuming a good 3D printer is available)
That was cute and a little magical. I may build one with my 8yr this winter break.
One suggestion - it looks like you could have a standard 'learn the cube' program where the webcam is off to one side of the robot, to remove that little bit of friction.
WCA Delegate here. The limiting factor generally isn't cost, but the need to handle cubes of various sizes and other puzzles entirely. Having a robot that can only scramble a 3x3 isn't useful for the majority of competitions.
"inexpensive". I love that. Like we're all searching for rubik's cube solver robots for our loved ones for christmas but they're all just too damn pricey!
It didn't say it's in high demand, and compared to the other solver robot you can buy (from Gan, probably the only one available) - 100-ish € - it'll certainly be cheaper.
I have a feeling though that this isn't about solving a cube but rather about building a cube solver o : - )
It is a bit slow, but it seems to work. Here are some videos: https://www.youtube.com/user/IAssemble/videos