You cannot casting Clear Casting Resin into Condensation Cure Silicones, but you can into Addition Cure Silicones. Most widely available silicones are Condensation Cure, Addition Cure Silicones tend to be harder, tougher and more expensive. We stock Silastic T-4 Addition Cure Silicone which work fine with Clear Casting Resin. Your silicone supplier should know whether your silicone is Condensation or Addition Cure.
Clear Casting Resin can be casting into almost any rigid mould; like glass, plaster, GRP, wood, plastic (but not polystyrene). However please ensure a suitable release agent is used, such as a wax like Mirror Glaze or Macwax.