For exterior pieces, Buffalo Plastering  & Architectural Casting uses glass fiber reinforced concrete - GFRC - a weatherproof material.

GFRC  is a thin shell cast material making it lightweight.  The addition of cast glass fibers [material made from extremely fine fibers of glass] acting as reinforcement creates durability without requiring embedded steel.

The lightness of GFRC also makes it an efficient and cost effective material to install. Where many similar products require massive additional structuring to hold their weight, this lightweight product can often be supported with only the existing studs and framing in place.

Paired putto/ acanthus leaf  grotesques: "... this insatiable desire of man sometimes prefers to an ordinary building, with its pillars and doors, one falsely constructed in grotesque style, with pillars formed of children growing out of stalks of flowers, with architraves and cornices of branches of myrtle and doorways of reeds and other things, all seeming impossible and contrary to reason, yet yet it may be really great work if it is performed by a skillful artist." - Francisco de Holanda, in his third dialog of Da Pintura Antiga, 1548.