Although I know nothing about the folding .32, I do have a couple of comments:
• At last, mystery authors everywhere have a gun about which to accurately write, "He released the safety catch of his revolver."
• Although this little folder is nothing like a practical weapon, it certainly is very thoroughly conceived and quite cleverly designed. Note, for instance, the small "ears" meant to shield the trigger finger from powder burns.

"Toolroom sample"? Very likely. Major parts of the little revolver are castings, still rough from the mold and not fully machined. They bespeak perhaps-handmade wooden forms used to make sand-cast metal.