Greetings-
I have done 3D, RTV mold makingand resin casting, but I have never cast vinyl.
I would recommend that you contact Dan over at Silpak, Inc. They're in California. I just met this guy and I do believe he knows everything there is to know about materials casting.
Tel: 818-985-8850, Web: www.silpak.com
By the way, may I ask what program you are using for your 3D drawings? Just curious.
Regards-