contest

Here I am waiting until the last minute to be creative. I'd like to make a gingerbread house for our Christmas party at home and I would like to have a fun contest for someone to win it. But....the tricky part is thinking of a contest that is age appropriate. There will be a 9 year old, a 7 year old, a 5 year old...and the twins but really...they don't count! haha. There is also a 17 year old and a 19 year old. What would be a fun fun contest that could involve all of them where everyone has a chance? Obviously an older child will win a colouring or drawing contest...I could pick a name out of a hat but that seems boring......

HELP!!!