In advance: Make royal icing details. Copy patterns and cover with waxed paper. Use tip 3 to pipe pull-out broom bristles, outline and pipe in mittens (smooth with finger dipped in cornstarch). Use tip 4 to outline and pipe in boots and shoes (smooth with finger). Let dry.
Attach 1 in. piece of licorice to backs of all with royal icing; attach broom to mitten. Let dry.
Bake cookie treats without sticks; cool.
Use knife to trim off hats for rounded snowman heads. Decorate with buttercream.
Use tip 2A to outline and fill in heads and bodies (smooth with finger dipped in cornstarch). Insert licorice string arms and legs.
Use tip 2 to pipe dot eyes, outline mouth and pull-out nose on all; pipe dot buttons.
For Earmuff Snowman, pipe tip 3 dot earmuffs; insert 3 1/4 in. licorice string for band. Pipe tip 3 outline scarf (flatten with finger); overpipe with tip 2 stripes.
For Top Hat Snowman, use tip 3 to pipe zigzag vest; outline and fill in scarf (smooth with finger). Outline and fill in top of hat with tip 4; add tip 3 outline brim and tip 2 outline band.
For Stocking Cap Snowman, use tip 3 to outline and fill in shirt and scarf (smooth with finger). Use tip 3 to outline and fill in hat brim; pipe tip 2 stripes and dot pompom.