Nice little decoration for your vehicle of choice. Show off your festive spirit with these little hand painted valve caps. 3D Printed with PETG. Polyethylene terephthalate glycol, known as PETG or PET-G, is a thermoplastic polyester that delivers significant chemical resistance, durability, and formability for manufacturing. PETG is an adaptation of PET (Polyethylene terephthalate) where the ‘G’ stands for glycol, which is added at a molecular level to offer different chemical properties. PET uses the same monomers as the glycol modified PETG, but PETG has greater strength and durability, as well as being more impact resistant and better suited to higher temperatures.