Myles
If I understand correctly, you are weaving cardboard strips and then covering with some form of mesh and plaster. My suggestion is instead of window screen which an be unruly, there is self adhesive drywall mesh that comes in a 6 or 8 inch roll. I double layered this and then added plaster. Just be carefull in brushing on the plaster as it will dip through. I am sure there are other mixes, but I like the plaster for its drying time and ability to take paint. Just a thought.
Ray Marion