Modular Picture Frame
A modular version of this picture frame. Folded from 4 units, each from 1:2 paper.
Modular version is easier to assemble and can be made with smaller paper sheets than the single-sheet version. This model also shows how the proportions of the frame (width, height, depth and breadth) can be varied independently. Instructions can be found here.
Inspired by models by Hans-Werner Guth who, as I later learned, has designed an almost identical model. Given the simplicity, I assume an exactly identical design must also have already been folded by others before. His work in turn is based on the designs of Thoki Yenn.