I am partial to Christmas trees with character - my little tree is a mix of store bought and homemade ornaments. A couple years ago, I made Christmas ornaments using clear glass balls filled with paint. It is super easy and produces a stained glass effect of color. A couple of mine....
christmas ornaments: make-your-own.
clear glass ball ornaments (can be purchased at a craft store like Michael's)
assorted paint (not necessary to use glass paint, but I did for the blue in the 2nd one)
Take off the top from the ornament. Use the plastic trays for drips and drying. Squeeze paint into the ornament, tilting to guide color down. The paint will pool at the bottom so sometimes you need less paint than you think! If doing 2 or more colors, allow to dry for a little bit in the plastic tray (maybe just make more!).
After about 30 minutes, move onto the 2nd color. Allow to dry without tops in the plastic tray for a week. Test before fitting top back on (the prongs will scratch wet paint otherwise). The bottom pool of paint will take a couple weeks to a month to dry completely but they can be hung on the tree while they finish drying.