Even Smaller Fella

I did not get satisfied with the previous Small Fella I made. This one works much better, and much smaller. A 555 photovore circuit is used. And I have made a case for 6V small batteries to power the bot. The capacitors have no function, they are for balancing the bot as it was falling without them. I have built 2 versions of it, here are the photos.
This one is much more balanced, since the motors are on the back.