process for duplicating old trim pieces posted by Steve C on January 16, 2000 at 08:19:16:
Hi, Steve. There are many latex or RTV products available for making molds. You can then make your part out of plaster, foam or resin. The products are available at industrial chemical supply houses. They are easy to use but expensive. The number of pieces that you want to get out of each mold will determine what product you want to use. Dow Corning makes some excellent RTV type products for multiple parts. The problem is that there are so many different products available that you should discuss your individual application with the chemical distributor. They should be able to guide you, but whether or not they will is another matter.
For a few pieces of small parts, you might also be able to find products at large model railroad oriented hobby shops.