Contact paper might just be the best thing. You can cut it to any shape, it stays in place, it removes cleanly and best of all... it gives you the ability to polka dot almost anything! I've even used it to polka dot the entry wall in our bedroom. It looks awesome, but it is easily removable for when I fall out of love with it.
To polka dot my laptop I used a circle cutter set to 2 inches to cut all the circles. Then, I just peeled and placed them into the pattern. I repeated this process at 1 inch for my Kindle, and a 1/4 inch for my phone. I love how something so simple can make everyday things much happier!