The gears are made out of MDF. They were painted to have a metallic look however the look I was going for was not achieved. Initially I was thinking of making the gears look like they were made of metal and left to rust for a few dozen years. I found some cool products that would give me that rusted effect but they were a bit too expensive. I settled for a can of Krylon Black Metallic Hammered Finish paint. The sample on the lid is a very nice black with subtle bit of gray. I think this might be from a bad batch since the final look is not as black as it should be. It also made taking pictures of the final clock a bit tough since even with modest lighting the glare was horrible.
The gear arrangement is as follows:
To achieve the correct timing the 9 tooth motor gear is advanced 4 steps every 9 seconds. By moving 4 steps at a time the motor routines can be simple since the motor is always at rest with the same coil energized.