If you use a shallow saucer you might get a hummingbird to use it for a bath. The original site is in Swedish. Use a Dremel drill and diamond core drill, a bottle neck diamond core drill would be even better, see Eternal Tools for these.
If you're searching for an easy and inexpensive easy way to decorate a wall, consider mounting a plate collage. Choose a colorful collection to brighten up a space — or light plates against a dark wall to create a uniquely sophisticated look.