Styrofoam Molds from Chef Rubber

Greetings!

Has anyone used the Styrofoam molds for casting sugar from Chef Rubber? Can you share which tricks you used to get your piece made without the sugar running out on the cracks of the Styrofoam? I have tried gluing the vinyls together but that does not work. I would like to give it another shot before I 86 it. (86 is a Las Vegas Casino term for getting rid of someone or something) :)

Thank you!
Nelly