Then Reinhart | Clemson University

Sabuda looks back and sees his naïveté as an asset when he began creating The Christmas Alphabet. "I knew nothing about nothing," he says. "No one had said there are only 10 mechanisms to make pop-ups. There were no bounds to what you could do."

That's why his work is unique. He has never been constrained by the strictures of the genre. Where others see impassable boundaries, he sees design opportunities. "The Christmas Alphabet in itself was so nontraditional that it set the tone for the level of freedom that now exists in pop-up books," Sabuda says.

Montanaro says Sabuda is one of perhaps a dozen paper engineers working today, and one of only a few able to make a living at his passion. And she says that while the books are owned by many children, it's adults who fully understand the remarkable engineering that goes into each one. "Robert's books really shifted the marketing from strictly children to adults and collectors."

EACH BOOK STARTS with a manuscript. Reinhart, who majored in biology at Clemson University and considered a career in medicine before going to Pratt, wrote the words for Dinosaurs because he was a dino fanatic as a child. Reinhart and Sabuda had previously done modest books on butterflies and beetles. "We wanted to do something a little bit more epic," Reinhart says. "Dinosaurs were it. Everybody loves them."

Once a manuscript is finished, Sabuda begins designing in three dimensions, cutting and folding card stock. When collaborating, he often does the roughs with refinements suggested by Reinhart and others in the studio. Then Reinhart, who began working with Sabuda in 1997 as a grad student at Pratt, creates the art, coloring the pop-ups using a variety of papers and techniques.

"With two-dimensional illustrations, you can do anything you want," Sabuda says. "In a three-dimensional work, a pop-up, it really has limitations. The paper will only obey certain laws of physics. You can't go outside those parameters, so there's a tremendous amount of problem-solving in those stages."