If you look around Google at the independent bookstores, you will find
Step by Step Compo and Mold Making for a modest $25 or so. Less than most of the current framing books.
Because I am a small independent business, I always dig deeper into the search results looking for another independent business. Amazon, et al are usually a last resort for me. But still there is a steady stream of brown boxes through my doors these days!
I recently had a conversation with an antique dealer on the subject of replacing missing ornamentation on gilded mirrors. His technique is to make a mold of a complete ornament using modeling clay. He then uses plaster to mold the whole ornament. But rather than cutting it to fit the missing piece, he removed the remainder of the missing ornament to avoid having to trim to fit.
I was initially horrified by this since it is more invasive than necessary, but the more I think about it, unless it is worthy of conservation which is beyond my level of skill, this method is more cost effective since it speeds up the process considerably.
I might give this method a try on some inexpensive thrift store finds to see how it holds up. I would probably use something less brittle than plaster, like Bondo, but most of my time when replacing ornaments is spent slowly trimming to fit.
