I had planned to post the findings I made with my soapstone mold but they are still looking a little rough. One of the drawbacks of casting this way is all the trimming and filing and I am considering how many of these I want to make. What I have instead is an ordinary household repair. A lamp I like very much was broken and I made a mold out of RTV cement and the patched-together pieces of the broken part. It held together just long enough to make the mold.
I wired together a temporary fix out of L brackets and it held the lamp on, but it looked awful.
This is the finished fixture. The replacement bracket is on the left. Not a bad fix if I say it myself.