I got to use HC-05 very popular bluetooth serial device, getting it up was pretty simple, also wrote my first android app
I made two projects for a Ad company
Dart gun control
A nerf type gun was used and it was controlled using android device with left/right up down control and shoot. It was rush project so could not document the whole thing but below are some videos I recorded during the build.
This is also a similar project as above, but shoots out paint, I used aquarium pumps which squirt out coloured water. There were four pumps used, I hacked a spike guard so in future more powerful pumps can be attached if needed.
The app were made using MIT’s app inventor and the firmware was on arduino.
I designed the parts in solid edge and the box design was made using http://makercase.com/