There are so many cool paper projects of folks creating origami and geometric amusements out of paper or cardboard or plastic that I was inspired to try. There is a plethora of 'flexahedron' examples out there (search for 'Andreas Markus Hoenigschmid' to have your mind blown).
However, I don't have any origami paper lying about so I looked on my desk and found some 3M Post-It Notes and Scotch tape and made do. This took five minutes, tops.
The goal is to make six tetrahedrons (A tetraherdon is a polyhedron composed of four triangular faces, three of which meet at each corner or vertex. It has six edges and four vertices. Wikipedia) The six tetrahedrons will then be joined by the adhesive tape at two of each of their edges as in the image above.