Another day I opened the girls bedroom door and found the whole room (wall to wall and floor to ceiling fan) had been turned into a giant 3 dimensional spider web with the knitting yarn tied around absolutely everything, my 3 yr old had worked on it all night and was very proud of herself. Since the little one never slept more than 4 hours a night, I guess she had more than enough free time no matter how much structure I crammed into the day.
We woke one morning when my son was 3 or 4 to find a similar structure extending all the way from our front door to our back door and covering half the width of the house. It was composed of long intertwined strands of tractor-feed printer paper chads. He had painstakingly separated them from 4 reams of paper. He explained that it was a burglar alarm system since you couldn't open a door or window or walk through the house without tearing at least one of the perforated strands, and the noise would alert us to the danger.