Sirpidol,
"Alumilite" is the brand name of the resin and as far as I am aware they have a number of products both for casting and molding (Someone else correct me if I am wrong here). What you would most probably need is some sort of rubber or silicone compund that can be used as a molding material and then resin can be used as the casting material to be put inside of the mold itself.
Hope this helps in some way. Oh Alumilite has a website with all its products on it and some tutorials aswell
www.alumilite.com
Regards,
Dublinguy