Taking molds for reproduction of metal objects can be done with an RTV (room temperature vulcanizing) molding compound, thus eliminating any heating effects on the objects. You can contact Dow Corning Moldmaking division (517-496-4400) as well as GE Silicones technical assistance (800-255-8886). They should each have products that will perform well and their tech people should be able to advise you. Another prudent call to make would be to the Getty Conservation Institute (check their web site for number) to get their recommendations as they probably have the best information on any possible reactivity and special needs. Good Luck Jamie Hascall Mount Specialist Hascall Museum Services Seattle, WA [log in to unmask]