I have some pictures of the prototype part. It's still curing, so you'll see some fingerprints on the surface, but those will come out if I choose to sand this thing.

First, a shot of the mold itself with the dowel for the keyhole inserted:


Next, a shot of the entire piece resting on the mold:


Last, a closeup of the entrance to the locking mechanism:


Fascinating stuff, huh? :-)

The next step is to cast the matching part for which I'll need more mold making supplies. I'm having trouble getting Alumilite products from my local hobby shop, so as much as I hate chain stores, I'll hit my local TAP Plastics for some silicone mold stuff and an epoxy kit.