craftgrrl | Painting on altoid tins

Hi, I have a slight problem... My craft is ugly!

I'm making marble magnets for Christmas presents, and they look awesome! My friend gave me a couple of heaping bags of empty altoid tins and my plan was to spray paint the tins, put little stickers on them and be done with it. My list of family/friends who get gifts is huge (30+) so painting seemed a non-time-intensive scheme. I primed and painted the tops. I didn't want to get the sides because I was afraid of paint effectively glueing the hinges and/or the sides shut.

So the tops look great. Can I just paint the rest? Will the sides stick? How do I make them look good without spending a lot of time or money?