Twigs, bark, pine cones, leaves, stones, acorns, flower petals, and many other objects make perfect building materials. You can pick flowers from your own yard, if you ask first.

A hidden site is usually best to keep your house safe—unless you want to put it where passers-by might spot it and smile.

Twig walls? A roof of bark or one thatched with leaves? A pebble path? A pine-cone fence? The options are endless. You might even furnish your house with, say, a nutshell bathtub, acorn lanterns, or a leaf hammock.

Time and weather will take a toll on your house, so you may want to take a photo to remember it. Of course, you can always make more—anywhere you go! At the beach, driftwood, shells, and seaweed can become a sandy village. When winter comes along, snow and icicles turn into new building supplies.