Sand the surface of the plywood siding using an electric sander with a medium-grit sanding belt.
Wrap 18-to-20-gauge chicken wire onto the plywood siding, keeping the chicken wire flush to the wall. Staple the chicken wire in place using a staple gun with 1-inch staples.
Fill a 10 gallon bucket with medium stucco grout, then scoop some of the grout onto a triangular trowel.
Spread a 2-inch thick layer of stucco grout over the entire wall using the trowel, refilling the trowel with grout as needed. Allow the trowel to make dents and swirls into the grout as you prefer to create a design.
Allow the stucco wall to dry for 18 to 24 hours.