A snowman made with plastic cups that adorned one corner of the stage of their Christmas Festival. To made it, they stapled the plastic cups. They used smaller cups for the head. This is a good idea to do a Christmas balls!
Here's a template for your Christmas Trees, just adjust theoutline to get the style you want but don't change the inside slot positions. A dab of hot glue from a glue gun will help to stop them from folding flat together ;