I built this giant version of the classic Spirograph drawing toy in my spare time over the last six months. The diameter is just under eight feet (2.4 meters). It uses sidewalk chalk to draw the lines.
I didn't keep track of the total time or the total cost, but I would estimate the latter at around $150 not including the new tools I had to buy.
Why? Because I wanted to see if I could, and because I love making things that surprise and delight people when they see them. Mission accomplished on both fronts.
Wouldn’t you just love to see a giant spirograph pattern on the road as you’re driving or walking by? Or even better, if you were to get a chance to draw one! -via Metafilter