I managed to bust one entire side off the the triangle style key leaving it vulnerable to snapping off the other side and losing the key. It's where the ring goes through and those with these type keys likely know what I mean.
To my surprise the putty epoxy I used, a Permatex plastic based product, did not stick, AT ALL, to the existing key housing. It just flopped off. What did work was cheap crazy glue to bond the epoxy repair to the key housing. It feels very strong and I hope it lasts. When the weather is better I plan to sand some of the excess epoxy off to give the gey a more rounded appearance.
My next task is to repair another triangle key I discovered that's broken in the same way, but this time I'm just going to pack the epoxy putty into the area previously occupied by the broken plastic, let it set, use crazy glue to anchor the new segment to the key housing then drill a hole through the epoxy plug to allow the key ring to pass thru.
For now here's a couple pics of the mess I made.