Burlap is fairly inexpensive, is sold in natural tan earth tones,
cuts easily, and drapes smoothly when hot-glued over a lattice
of corrugated cardboard strips.
The grade that works well is available at fabric and craft stores
like Jo-Ann Fabrics. The price varies significantly depend-
ing if there is a sale going on. We were lucky and bought
an initial 10 yards for about $20 when it was on a 40% off
Fabric, cardboard,
hot glue, scissors and
plaster are cheap
and easy
See this layout
at the Portland
NMRA Convention
in August 2015