I am building a diorama using historically accurate contour mapping. To achieve the desired level of accuracy, I am building the terrain in layers, with each layer corresponding to either a 1-foot or 2-foot contour interval. To achieve realism, I must then "smooth out" the spaces between material layers using a shapable medium, like drywall compound.
To save time and expense, my preference is to build using 2-foot contour layers. At my chosen scale, each layer is 4mm. The most economical material appears to be 4mm Coroplast, a plastic (pvc?) board with a physical structure similar to that of corrugated cardboard. The trick is, I don't know if drywal compound will stick to it. I will need to transport the diorama multiple times, and I'd hate to see drywall compound delaminate from the Coroplast surface. Does anyone have experience with this combination, or could anyone offer advice on materials or techniques I could use avoid the perceived problem? Perhaps there is some type of primer or coating I could first apply to the Coroplast to improve adhesion?
Alternately, I could build 1-ft contours using 1mm Art Board. This would be a cellulose-based board. I anticipate adhesion of drywall compound would be less of a problem, but I am worried about the Art Board soaking up the moisture from the drywall compound and selling up or delaminating or otherwise being ruined.
Any advice is greatly appreciated. Thanks!