Is your friend into stamping or scrapbooking? What are her interests? You could decorate a paint can around something like that. Or, if you've known her a long time and have had lots of fun times together, tuck into the paint can things that will remind her of your fun times. Movie ticket stubs, products from a particular coffee shop if you like to meet her there, her favorite toiletries or candy or fingernail polish color - whatever speaks of your friendship with each other and her favorite things. And homemade cards so that you can keep in touch!