For over a decade, Paul Johnson has been passionate about making pop-up tree houses. In this one-day session, Paul combines several paper engineering techniques into a tree house constructing workshop. The tree grows in stages: trunk and then branches, and, finally, a fairy-tale house that crowns the upper foliage. The whole structure has no folds—the flat state of the form transforms into a 3D pop-up with one flick of the wrist.