Have you seen this site? http://woodsshop.com/Chashitsu_Plans_Chashitsu_Plan.htm

Hi:

I made a Japanese inspired wall/fence (see link below, in this post...those pics are from the initial construction) using plywood as a base, and covering it with a mixture of outdoor paint and sand. You mix some sand with the paint before painting the surface. I used three coats. Experiment with the mixture...it's not critical. The result is a stucco look with less work.

I put silicone sealant around the edges of the plywood to prevent water damage. It has already withstood two Ottawa winters and is in great shape.

Here is a link that might be useful: My Japanese garden fence/wall