v. Double Slit method

When you draw a line on the sketchpad, Pop-up Maker create "double slit (one of pop-up techniques)" by generating folding lines and the other cutting line. The following pictures show how Pop-up program generates a double slit; 1) a user sketches a line in the sketchpad. 2) Program creates folding lines and a cutting line to make double slit when you fold a card.