Got this from a website ... intended to try but never have ...
Items needed:
fresh oranges, cut in half, scraped & cleaned out.
a couple of glasses
tin foil
Preheat your oven to 200 degrees. Cut a fresh orange in half and ream out the juice. Scrape all the inside flesh out then rinse and pat dry. Take a small piece of tin foil and cover the bottom of a glass. Push an orange half over the bottom of the glass onto the foil. Do the same with the other half of the orange with another glass. Put the glasses on a baking sheet...orange faces upwards, the drinking side of the glass is upside down. Place in 200 degree oven and dry for 2 to 3 hours. Once done, the two pieces should fit together like a little box. If you want,you can punch a little hole in the top of the orange and put a ribbon through it. Or you can decorate the top of the orange with fun stuff, such as seeds, star anise or anything else you can think of....
hope this helps