This coronavirus cap is made up of two types of “stems,” one with a hexagonal base and one with a pentagonal base. They are held together with small elastics to form part of a truncated icosahedron (soccer ball) shape. The tension of the elastics holds the cap in place on your head.

The size can be customized to fit specific head shapes by varying the type of elastic used and distribution of the two types of “stems” relative to one another.

The model above is held together with 4mm orthodontic elastics. Orthodontic elastics work well because they are strong for their size. Other small elastics will work as well.

The basic form of the cap requires 6 pentagon stems and 15 hexagon stems.

Start with one pentagon stem. Attach 5 hexagon stems to the edges. Surround theses 5 hexagon stems with another 5 pentagon stems. Put on a last ring of 10 hexagon stems. You can leave the cap this way, but you might find that it does not grip your head very well. To customize the fit, add a few additional pentagon stems between select hexagons stems in areas that need to be tightened up a bit more. If you need to open up a section, try replacing one of the pentagon stems with a hexagon stem.

The model pictured about has an additional 3 pentagon stems to tighten the front and sides, for a total of 9 pentagon stems and 15 hexagon stems.