90° Pop-Up Cards
90 degree pop-up cards are designed to be viewed when opened part way (at a 90° angle). If you open these cards all the way the pop-ups become flat again, because they are cut and folded from a single sheet of paper.
The sides of a 90 degree pop-up card can make a floor and a wall, or create a corner if the card is held upright. This style of pop-up card is often referred to as “origamic architecture,” even though they can represent many images besides buildings and architecture.