As solar cooker design continues to evolve, and provide better cooking efficiency, there is an increased interest in finding more highly reflective materials to better redirect the sunlight. Polished metal surfaces have been tried, and while effective, tend to be costly solutions. Metalized polyester film correctly bonded to plastic Coroplast sheeting is a still economical approach for users wishing to create their own reflectors. Elmo Dutra, a professor and solar researched from Brazil, explains one such approach in Making the Petals of Solar Cookers with Mylar and Sheet Coroplast.