Welcome to my Forum Bannette - To make a of a glass slipper, you would have to make a two piece mold. You can read about this process at the following links:
http://www.makeyourownmolds.com/how-to-make-two-part-mold
http://www.makeyourownmolds.com/how-to-make-two-piece-mold
http://www.makeyourownmolds.com/how-to-make-3D-mold
It would be good if you looked over these links and then we can talk about specifics concerning the glass slipper. Also, tell me how big the slipper is that you want to make a mold over and what is it made out of.
bannette - let me know when you have looked over the tutorials
Dominic 
Hi Bannette - Here is a picture of a clay up of a shoe that Charity George made for a shoe mold she used in the ultimate cake off challenge. She used CopyFlex to make the mold. Do you see how this method resembles the tutorials on how to make a two part mold? When the mold was finished, she poured the sugar through the sole of the shoe which formed a access hole into the mold because it was flush with one of the sides of the mold box.
I took a class from Dominic last night and we made this shoe. It was the easiest thing I have ever seen?
It turned out perfect and very delicate looking.
Wow, people with a shoe fetish are going to go crazy when they see how easy it is to make a shoe with isomalt and Dominic's products.
Chiara - I really had fun two nights ago with you all. Now you know as much about Isomalt as I do.
Thanks for posting your comments
Dominic
You know I'm glad this came up because I want to expand my chocolate shoes but I haven't figured out how to get around some of the problems, -- this will help tremendously!! Thanks for posting! 
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