You mentioned shrinkage in the RTV rubber mold and resin casting processes. Others have mentioned shrinkage as well. It must be significant if it is mentioned so often.
Is there a given size or volume above which shrinkage matters?
Does the rubber mold shrink?
Do resin castings shrink a predictable amount or are we talking trial and error?
Is shrinkage expressed as a per cent?
Do various resin concoctions shrink at different rates or all the same?