Preheat oven to 200ºF.
Beat egg whites, salt, and vanilla until foamy and white.
Continue beating while adding sugar, a few tablespoons at a time.
You can also add a few drops of food coloring at a time while beating until desired color is reached..
Beat egg whites until stiff peaks form.
Transfer to a piping bag fitted with a decorating tip. I used Wilton #21 for the small trees, and 1M for the large.
Pipe onto parchment lined baking sheets in a zigzag pattern, starting small at the top, and larger at the bottom, finishing with a short tree stem in the center.
Sprinkle lightly with desired sprinkles.
Bake in center of oven for 1 hour, then turn oven off, and let rest in oven for another hour.
Remove from oven and let cool completely.
Attach a star to the top of each tree, using a small amount of decorating icing.