“Castle” is a New York Times bestselling popup book, written and paper engineered by Kyle Olmon and illustrated by Tracy. All other projects are paper engineered and illustrated by Tracy. The walrus in the clock tower is part of a series of make-it-yourself “Paperland” projects which fit together like a 3D jigsaw puzzle. The angel is a free tree-topper available at Seafarer Baking Company. The paper kaleidosope and Santa at the palazzo are holiday giveaways for Horton Plaza. “A Visit to the North Pole” is a popup book about the adventures of polar bear, searching for Santa on Christmas eve.