2-3 days in advance: Make trees. Prepare and roll out Roll-Out cookie dough. Cut using classic fir cutter from set. Bake and cool cookies. Outline using tip 3 and full-strength color flow; let set. Flow in with thinned color flow. Let dry 24 hours.
Also: Make snow people. Prepare shortbread dough. Press into snowman cavity of pan. Bake and cool.
Decorate snow people with buttercream. Ice smooth in white; tint icing for trims.
Using tip 3, outline and fill in hats, patting smooth with fingertip. Using tip 3, pipe dot buttons; outline and fill in scarf and apron, patting smooth with fingertip. Using tip 1, pipe dot eyes, outline mouth, outline hat bands and hat buckle. Pipe tip 2 pull out noses.