Last year, we featured a wall monitor made of ping-pong balls cut in half. It was an awesome hack and a great idea. Ping-pong balls were cut in half to perform diffusers for the hidden LEDs underneath. Here is another ping-pong ball hack used as display pixels. This time, the balls are kept spherical. This hack was made by Mike Szczys from Hack a Day. Based on the ATMega8 and on the DS3232 RTC chip, he made this nice large wall clock. Keeping the balls spherical gives a nice 3D-effect!