Thanks for sharing and raising memories. I will plead mea culpa now since I have not become innovator, guiding light or even two-bit contributor to resin casting at the commercial level.
When you mentioned the Dow or GE rep it reminded me that decades ago I worked at the corporate labs of the now defunct GTE Sylvania. At that time I did not even have a business card since I was a Technician. However, part of my job was to prepare test specimens for thermal shock and tensile testing. The test material happened to be epoxy for encapsulation of large power transformers to replace the use of hazardous material coolants. I cast the test samples in Dow Corning 3110 RTV.
Back in the day, distributors would take orders from regular folks so I ordered a kit that included a 1lb can and a tube of curing agent. For my first attempt I used a cast metal flat car end as a master, then the end of an Alco RS-11 hood for the number board detail. I made my own master of a Lionel caboose running board so I could repair a car I bought at estate auction. For a couple of years I used it to make a variety of small parts using any 2-part epoxy compound I could buy at the hardware store. No investment in experimentation there, and it showed sometimes!
I was having moderate success and envisioned larger projects so ordered a carton – eight 1lb cans IIRC. It was a large cash investment for a young married guy with a bunch of kids, wife and mortgage. Then life overtook any hobby activities for quite some time and about three years ago, after a couple of moves I finally opened the carton (after building some masters) only to find it had sufficient time to self-vulcanize over the intervening years…so much for my casting career. Now I am not able to locate any distributors except for commercial sales and they want a Purchase Order to boot. I am sure there are also much more suitable molding materials today, but I really liked that Dow 3110 RTV!
Anyway, thanks for the memories!