What manufactured board might you choose to make a long shelf for heavy books?

Medium-density fiberboard (MDF) would be a suitable choice for a long shelf to hold heavy books. MDF is a dense and strong type of manufactured wood board that is made up of wood fibers that are glued together with resin. It is uniform in composition and has no grain or knots, making it less likely to warp or bend. MDF is also strong and durable, making it well-suited for heavy loads such as books. Additionally, MDF is easy to work with and can be cut, drilled, and shaped using standard woodworking tools.