Woo hoo! Working collision model, baby!
Had the damndest time figuring out how the whole concave collision thing worked. I knew concave collision models were made up of a series of convex objects arranged to create the EFFECT of concavity, but while my approximations fleshed it out alright, the compiler kept telling me I had 2 dimensional geometry and that it was scrapping a concave object for a "shrink-wrapped" convex object. It still worked in GMod, but you couldn't stand on the platform or anything.
Eventually found out my collision objects needed their smoothing groups to be consistent, and this ended up being the cause of the error. A quick fix, and voila, Rhonda can use that water tower for shelter from ol' Stumpy :-)
... of course, she couldn't use that ladder, as ladder functions are built into map entities, lol.
Also, I worked around the material settings for this a while, not satisfied with how the cubemaps played havoc with the shading. I got frustrated eventually and deleted the Cubemap material setting entirely, and... well, it rid me of that damned reflection. I'll be sure to experiment with that on the creature models too. Those damned environmental cubemaps are best used for surfaces that WOULD end up being somewhat reflective, like glass or shiny metal or tile or water. If I can do away with those entirely, it might really add something (ironically) to their overall look in the engine.