Jon,
VSSSD works well as a texture. it is NOT structural. If you want a boulder that people can sit or stand on nothing is going to work applied over
chicken wire except, maybe fiberglass, several layers of it. If you want structural you will want to slice up the boulder, just like a slicer for 3d printing, and
build it in layers or make vertical ribs with
blocking or lathing in between. you could then wrap the boulder with
muslin or cheese cloth, then use
VSSSD on top of that to create final texture and color. Below is a shot of the
edge of a
platform for "The Flying
Dutchman" -Sarasota Opera <can't remember the designer>these were intended to look like sheet ice so were, mostly,
flat on top. they are made from a layer of 3/4" ply, 8" layer of bead foam, another layer of 3/4ply, then cheese cloth. the
VSSSD was applied in and extremely thin gray layer the top coat painted for
effect.
Another great way to construct is to
build a shell out of 3/4" or 1/2" ply cut like
pattern pieces, scab/tack it all together like assembling a 3d
pattern, then
build appropriate framing. fill gaps at seams with foam, add wads of glued up newsprint for random perturbances,
cover it all in
gauze then go crazy with the scenic dope.
Hope some of that helps. Boulders and rocky sets can be difficult without having
flat walking, sitting standing surfaces designed into them .