Styrofoam will be used for payload section.

Styrofoam is a superb building model material that consists of a thin sheet of foam sandwiched by two layers of paper (or other laminate). The result is a very lightweight but stiff section of material that can be cut cleanly with a sharp knife yet remains durable and rigid.
Foamboard is commonly called “Fome-Cor” (or Foam-Core) as well as a variety of other trade-names and generally comes in thicknesses of 3mm and 5mm.