HARDBOARD.
Hardboard, also known as high-density fiberboard (HDF), is a type of engineered wood made from wood fibers that are compressed and bonded together under heat and pressure. It's denser and stronger than MDF, with a smooth surface on one side, making it ideal for applications like backing for furniture, paneling, drawer bottoms, and even as a painting surface.
It’s affordable, lightweight, and easy to cut, but it’s not great in high-moisture environments unless treated.