I saw the demo video for the neurowear "necomimi" brain controlled cat ears and I thought they were pretty awesome. I'm just starting to learn electronics and I thought a fun project to start out would be making my own version. Sadly, I don't think I'm adept enough yet to take on making my own EEG and I don't think the EEG's that are available are very reasonably priced, so I settled for having a button input to control the cat ears.
I wanted to build something that wasn't too expensive and was easy enough to be done in a sitting or two. I picked out some cheap servo motors, some craft supplies, spent a weekend or two developing code to control the servo's from a microcontroller and after much trial and error, I built some kitty ears that I think are pretty decent.
Here's a video of my lovely assistant using the Kitty Ears: