This is fun, easy and very inexpensive! you can purchase your normal glass christmas ball, or even use old worn out balls from your past.
You just dip them into a solution of salt, water and vinegar (don’t forget to put the solution inside also). This will remove all the paint and you will be left with a clear ball. Rinse, let dry completely, then simply put a teespoon of unpopped popcorn kernels inside the ball. Place the ball in a paper lunch sack and put it in the microwave.
Pop about 1 minute on the high setting. I have had a few I had to pop just a few seconds longer to get the popcorn to pop well. (By the way, be sure to leave the metal top off while microwaving.) When corn is popped replace metal hanger and add a bow or whatever decor you please.