An ingenious Victorian Metamorphic Combination Table, Desk and Chair (shown open and closed above) was made of oak after a design by Stephen Hedges. Other similar examples are housed in museums in New York and New Orleans.
Golden Mean Calipers go beyond measuring a single distance. They show two distances that are in the perfect Golden Mean ratio to one another! For a smart DIY project, make a cardboard model that shows a ratio of your choice, like or Pi.