You can use any of our 4X silicone mold rubbers for pewter.
If you wish to do really low temperature mold making, a vulcanizing
silicone we introduced in 1994 called LS-250 can be cured at 180F.
Additionally, we can offer our 2 part clear silicone RTV (liquid),
which cures within an hour at 125F.
Please call me for a sample.
Zero-D Products, Inc.
Precision engineered materials solutions
800-382-3271 in USA, Mexico and Canada