Text and diagrams by Jane Rosemarin
Three Balloon Boxes folded by Jane Rosemarin. Diagrams tested by Marc Thompson. See PDF diagrams.

Sweet Paper creates the sort of useful geometric models I love. You can find them on her YouTube channel. The Balloon Box, or Secret Box (because it looks like a one-piece icosahedron when made with two sheets of the same pattern) makes a lovely decoration, and you can put a gift or treat inside. It’s sturdy and satisfying to fold. In this article, I’ve linked to my diagrams for the Balloon Box (above) and also embedded Sweet Paper’s instructional video (below).

I learned the box from the video last December, and I taught it to a handful of friends that included Kathleen Sheridan of the Origami Connect committee. Afterward, Kathleen asked me to teach the model as part of that series. In the process, I made step drawings to show during the webinar. Having gone that far, and with Sweet Paper’s permission, I turned the drawings into the diagrams published here.

The model requires two sheets of A-proportioned (1:\(\sqrt{2}\)) paper. Decorative papers look good, and two coordinating patterns or a pattern and a solid are especially attractive. For your first try, choose a pattern (or solid color) that doesn’t hide the creases and a paper that holds a crease well. Please don’t use foil or a paper that tends to crack. Only one side shows in the finished model.

Here is a table of paper and finished model sizes:

Paper Size Width of Finished Model
A5 57mm
A4 74mm
8½″x 6⅛″ 2¼″
11″ x 7¾″ 2¾″

Sweet Paper’s YouTube video: