What paper stocks can I choose for cheap coroplast signs?

Coroplast signs aren't printed on paper. They use corrugated polypropylene, a fluted plastic engineered for the outdoors.

• Standard material: 4mm corrugated polypropylene with full-color digital printing.
• Weatherproof: waterproof and resistant to rain, UV, and temperature swings.
• Lightweight but rigid: the fluted core keeps the panel stiff on wire stakes.
• Common uses: yard signs, real estate signage, and temporary event displays.