Being a huge fan of Star Wars, I just had to create that cute little droid from The Force Awakens, BB-8.
I started by putting a wheeled robot in a plastic ball and tested its movements. Apparently, I still have to add a bit of weight to keep the ball stable when it suddenly changes direction or speed. The head I downloaded from Thingiverse from a maker called MaxterOne, you can find his design here.
The electronics still need a lot of work. I figured the best thing would be to have the body follow the orders sent to it by the head via RF and the head would be controlled by a mobile phone via Bluetooth. I am still working on this. In addition, the head does not stay on the body, that needs to be done with magnets. I also need to fix that. Below a collection of pictures I made during the construction.