Synthetic felt is composed of man-made or artificial fibers, predominantly polyester, and other materials such as viscose, nylon, acrylic, or a blend of these fibers. Polyester refers to a broad category of synthetic polymers, with PET (polyethylene terephthalate) being the most common type - interestingly, it's the same material used for manufacturing plastic bottles, and it is a recyclable material. Originally, synthetic felt served as a cost-effective substitute for natural felt, chosen primarily for its affordability.