High-density polyethylene (HDPE) or polyethylene high-density (PEHD) is a thermoplastic polymer with a high strength-to-density ratio. HDPE is commonly recycled and has the number “2” as its resin identification code.

HDPE is a terrific material to use when constructing robots. Bolt it to two separate components to add some rigidity or use it to cover an area to keep items out. This is a single sheet of HDPE plastic, cut to a 24×24 in. square.