Terraforma plaster bandage.
150mm x 2.75m
Used to make landscaped relief such as hills, embankments, cuttings etc.
It dries to form a rock hard, but light structure.
On a base board, use screwed up damp newspaper to design the contours, then cover with 2-3 layers of soaked Terra forma.
Working with plaster is messy, protect your work surface with a tarpaulin sheet.