This is the back of the clock, pictured here with the discontinued USB Boarduino. As stated before, this project works great with the Trinket 5V, Arduino Uno, Metro or other Arduino compatible microcontroller board!
I used a spare circular piece of black plexi to hide the electronics behind, since I'm just hanging the clock near a desk.
If you want to you can create a more sophisticated enclosure for this clock. arradan created this enclosure to 3D print on Thingiverse!