Popular craft activity. Make a Christmas Tree and cover it with sweets
Sheets of fairly firm card to make into a cone shape, double sided sticky tape, sweets to stick on (chocolate M&Ms worked well). You can also use stryofoam cones. Silver card for stars.
Make a cone out of the card, and cover the card in double sided sticky tape. I did this in advance to save time. Give the YP a bowl of sweets and get them to stick them on the cone covering it completely. Stick a star on the top.