I made a green one of these too, but I dropped it on the floor and stepped back on it. :o(
Blown eggs take watercolour paint really well, then I used a silver gel pen to draw on floaty feathery shapes before painting with pale pearlised nail varnish to protect them and give them a lovely sheen. I used coloured glitter glue to add to the feathery-ness after the nail varnish dried.
They are light enough to thread with ribbon or cord and hang from the most fragile of branches. They could be decorated with whatever holiday theme you like, but I thought feathers were quite appropriate seeing as they are birds eggs! And you can make yourself an omlette with the contents! :o)
Ria S. posted this project as a creation without steps
Here are some similar tutorials to help you make this one!