These were one of the ornaments we made for our Cookie Baking and Craft Day.
First we dripped acrylic paint into clear glass ornaments, making sure to get several good drips of different colors in there. Then we shook them around (while holding a paper towel to the top hole so no dripping out–actually some did drip out, and onto my good jeans, and my shoes, and on the floor, etc.) til all the sides are covered. Let sit upside down to drain; theoretically until they’re dry, but we were impatient, so we hot glued the metal cap of ornament back onto the top. The colors still mingle as they dry and created this lovely look on my ornament. Less paint, and not as much color mingling- I noticed. I hope you like them and are inspired to try your own!
This is the pic of the ornaments we were trying to recreate via
Do It And How 