Once, when I was about 10, I found an ad for do-it-yourself hovercraft plans in the back of a Popular Mechanics magazine. I spent the rest of that day consumed by Walter-Mitty-esque daydreams in which I zipped to school on my own personal flying saucer, the envy of all my classmates. That evening, I asked my dad (a man clearly lacking in vision) to loan me the necessary $4.00. He was unmoved by my enthusiasm and refused. Sadly, my fantasy never became a reality.