Anna! Are you talking about using old lightbulbs? I'd love to know more info. At first I thought you were using bulb pots that are ready made. My bowling ball isn't painted. it's made of cut mosaic tiles and glass globs.
I have painted a few outdoor things with common acrylic paint which I then sealed. They do fade over time, but last quite a while. I just never expect things painted with acrylic to be permanent.