Add the Jell-O powder crystals, stirring constantly until it is mixed in well. Pour marshmallow mixture over the popcorn, stir and roll into balls. In medium saucepan, combine margarine and marshmallows and cook over medium heat until melted. Add food coloring and mix well. Pour evenly over popcorn stirring quickly to coat.
Shape popcorn into a cone shape and decorate tree with candy pieces.
Pour over one batch of popped popcorn quickly and mix well. If you overcook, it will have a more gritty sugar texture. Melt butter, add sugar and Karo syrup, bring to a boil, stirring and simmering 3 minutes. Stir in vanilla, pour over popcorn and mix well. Let mixture stand 2 minutes to cool.