I decided to built this "life-size" Railroad Crossing Signal because my son at the time seemed to be obsessed by them. He loved hearing them and was always excited because he knew a train would soon be approaching. So I decided to build one he could turn on anytime he liked. It has working lights which oscillate about once per second. It also has a mechanical bell which dings each time a light shines. The construction of the mast is mostly out of PVC pipe which I welded together and painted with "Hammered Metal" spray paint to make it look metal. The cross bucks and signal borders are made out of 1/8" hardboard. The signals themselves are made from automotive trailed tail lights. Finally the base is a hollow 3/4" birch plywood box painted flat black.
It was an incredibly fun project to work on. My son seemed to enjoy it as well.
Click here for a PDF version of the schematic of the circuit I built for this.