I make two holes(like a button) in the base of my bottle caps and sew the plain caps on first. Then I glue the image in after. A dab of hot glue under the cap before you sew helps a little too. I don't think it looks bad at all when I'm done since the thread isn't really bulky and the image still sits flat. I can't tell the difference between mine and others I've seen using E6000. My friend uses a little bit of sand paper to roughen the bottom up a little before she glues, and she has success with that.