I signed up at Craftsy to take a course by Alice Medrich called Decadent Chocolate Cakes, and one of the cakes she wraps in chocolate. She suggests using plastic shelf liner or Mylar or Duralar (.005 thickness or greater) for hers. You can get it at a hardware store. I guess that is another option if you can't find acetate. Just make sure you put the chocolate on the smooth side and not the ribbed side.
Thanks for posting the tutorial. It's super awesome!