I came across this Aircraft Navigation Beacon circuit and thought it was an interesting trick to achieve with some 555 timers. It runs white LED beacons that flash twice then delay 2 seconds before repeating. This simulates anti-collision strobe lights for aircraft.

After a few tweaks found the circuit works reasonably well, however it is very touchy and component values need to be carefully selected in order to get the timing right.

To show the circuit off a little better, I fashioned a little aeroplane model from some popsicle sticks that sits proudly atop a 9V battery.