You want to bake a special cake for your mom, so you boot up the 3-D printer in your kitchen. Loaded with a dozen cartridges filled with pastes of chocolate, marzipan, and other ingredients, the machine downloads instructions from the Internet. You key  in a specific texture, size, and flavor, and then you insert a 3-D message in the center—Happy Birthday, Mom!—to be revealed only after she takes a bite. The machine does the rest, assembling and baking a pastry so scrumptious it rivals a virtuoso chef’s in richness and complexity. Your mother loves it so much that she insists you send a slice of the same cake—in the form of a digital recipe—to your Uncle Norman’s printer as well. Your 3-D cake recipe gets so many raves, in fact, that you decide to sell the recipe online for 99 cents a download.

Science fiction? Hardly. The technology exists, and over the last eight years people have cooked up all sorts of comestibles with it, some a lot stranger than a cake with printing inside. [See More]