You probably have seen different versions of this Box Monster on Pinterest. The one I made with my students was out of tissue boxes. When I asked parents to send in boxes, one sent in a bunch of latex glove boxes that had curved openings. They looked like smiles (or frowns depending on your perspective.)
These monsters are quite versatile. The original ones I found on Pinterest were tattle monsters. I used them for Valentine boxes the past two years. This time of year, I am looking for some different creative writing ideas.