All molds are made by hand. Simple forms can be cast easily, but often it’s more complex and molds will be made in different segments and divided in parts. It requires a lot of experience to create the perfect mould.
The rubber mold is made with two-component rubber, that is mixed, made vacuum to get the air out - it resembles cooking - and then poured over the prepared object that will be cast.
When the mold is ready, the resin is poured into the mold and placed in a pressure tank to get the air bubbles out.