Most plastics are long organic polymers with a high molecular weight. When these long chains of monomers are prestretched in their manufacturing they have a relatively high level of organization. When heated to their glass transition temperature, these prestretched plastics will contract in the dimension that they were prestretched. With the use of pigments, (and in our case, biopigments) we can select where and how the prestretched plastic contracts. By drawing these pigments on the plastic and using infrared light from the sun, we can make the plastic fold. This is because in a flat sheet of prestretched plastic, drawing a dark line on the plastic will allow that section of the plastic to heat up and contract faster than the rest of the plastic. Having the dark line only on one side of the plastic will cause the plastic to fold toward that side as seen in figure 1.

By having plastics fold, we can quickly prototype new designs of self-folding by simply printing on biopigments onto plastic sheets and applying infrared light to the plastic. These designs can range from simple cups and containers to complex solar sails and arrays.