A gnomon is a structure that casts a meaningful shadow, for example, the blade of a sundial or the tip of an obelisk. In the original Greek, "gnomon" means "one who discerns or examines". It is a 6000+ year-old technology. To update it for the 21st century, we came up with a way to CNC-machine a double gnomon so that instead of casting a static black-and-white silhouette, it produces a dynamic (=animated) continuous-tone (=greyscale) image. We just shipped a 15' interactive sculpture to Burning Man in which 2-4 people ride on swings to activate a gnomon. The gnomon casts an animated image of a skull, which turns to look at each participant as they swing forward toward it (see project videos on website). This sculpture will be exhibited on the Kendall Square plaza when it comes back from the playa. We'll have docents around to offer rides to the public and explain the technology and its connection to ancient art and architecture. For that, we'd like to cut additional gnomon animations to swap into the sculpture -- skulls play well at Burning Man; but for Cambridge we'd like to have some more locally resonant designs. In particular, we hope to use this opportunity to show the art form's versatility to representatives from the city, in support of a proposal to put gnomon-style animated shade screens into public amenities such as the roofs of bus-stop shelters and shade-structures in parks.