Make cookies. Prepare cookie dough according to recipe. Roll out to 1/8 in. thick. Cut out using snowflake cutter. Bake and cool.
Prepare and tint icing. Prepare royal icing according to recipe. Divide icing into two 1/2 cup portions and tint 1/2 cup of icing Steel blue and Caribbean Green using color combinations. Combine Delphinium Blue and Royal Blue for Steel blue. Combine Kelly Green and touch of Teal for Caribbean green. Reserve remaining white.
Thin icing. Thin Steel blue and Caribbean green icing to count of 18. Thin 1/2 cup of white icing to count of 18. Reserve remaining full strength white.
Prepare and fill bags. Prepare 3 parchment bags, fill separately with thinned icing. Cut 1/4 in. off the end of the bag.
Flood cookies with thinned Steel blue. Let dry 4 to 6 hours. Prepare a parchment bag and fill with thinned steel blue icing. Cut 1/4 in. of the end of the bag. Pipe a thin line of icing and attach white and light blue jimmies. Let dry 2 to 4 hours.
Flood cookies with thinned Caribbean green. Let dry 4 to 6 hours. Prepare a disposable decorating bag with tip 3 and full-strength white icing. Pipe lines and attach snowflakes to points. Let dry 2 to 4 hours.
A) Flood cookies with thinned white. Immediately cover with blue sugars. Let dry 4 to 6 hours. Brush off excess sugars. Using same full-strength white bag with tip3 from step 6, pipe lines on top of sugar. Let dry 2 to 4 hours.
B) Flood cookies with thinned white. Let dry 4 to 6 hours, reserve bag. Use reserved bag with thinned white icing and pipe thin lines of icing, doing small sections at a time, on top of dried cookie. Immediately cover with nonpareils. Let dry 2 to 4 hours.