HEXBUG nano is a fun toy which moves like a real bug. I want to use it to surprise someone who open the box contain a dozen of the HEXBUG nano. But the HEXBUG have only a toggle switch for activation, so the bugs cannot hide silently in the box.
We can add a photo switch to activate the bugs only when they come to bright place. It works well, and the modification doesn't change the look of HEXBUG nano.
It is very simple circuit, but little difficult when you solder SMD transistors. Check the schematics.