These darling Charlie Brown Peanuts Christmas ornaments were made by Hannah Durflinger! She used glass bulbs and acrylic matte paints to make them. You could use black paint on top or a sharpie when they're dry. Perfect to hang on the tree or give for gifts!
I also came across this idea on Pinterest (let me know if you made them!) but it looks they put the paint inside glass bulbs and decorated the outside with sharpie. The description said "Buy clear glass ornaments, acrylic paint thin enough to pour into ball and coat, black sharpie for outside. NOTE: If you make a mistake drawing nail polish remover will take it right off and you can start again."