The "lightbulb" is a 5-sided spiral that forms the general shape of a lightbulb. I made this a few years ago as a test piece and I've updated it just for you.
I've included two sizes:
Full size: about 4.8 inches tall
Half size: about 2.4 inches tall (...yep, that's half...check!)
I've also included each STL file in two resolutions.
I was able to print this without support on a Rap Man. The only tricky part is the merge at the top. It is fascinating to watch the arms be built up, especially when they are just about to be connected. More recently I printed it with my new UP! printer, but wasn't able to completely disable supports, and it was a real job getting the support structure out. Don't print with supports unless you have to.