I am making a ring box cake for my son's engagement party and would like to make the lid out of styrofoam and cover it with fondant. How do I get the fondant to adhere to the styrofoam?

My preferred method is to massage the dummy very well with crisco and apply the fondant.

You need to smooth the upper edge--either roll it on the countertop or sand it down with an emery board/nail file--so that the fondant doesn't tear.

You can also spritz the dummy with water, use piping gel, or corn syrup. I just think the crisco gives you some extra time to finesse the fondant and if you have to re-roll it, it's not real sticky.

HTH
Rae

Rub some shortening on the styrofoam then add the fondant.

same way that you would on a regular cake, is my guess - put a layer of buttercream under it.

Thanks, Rae - I added my $.02 before I read all of the responses and hadn't heard of using crisco before - I will certainly try that ... I'd bet that it makes it a lot easier to clean up styrofoam forms, too!

Thanks everyone. He popping the question on Saturday and we having a surprise engagement party for her with all the family and friends afterwards. It is all very exciting

You can also brush piping gel on. It actually prefer it now over shortening but either one works well.

Cheapest method of all - spritz with a bit of water then cover with fondant.

Actuallly do not put too much Crisco on it as it can deteriorate the Fondant. I light coat will work just is well. Be sure to get the corners well as that is an area that likes release! Be sure to use Crisco, not any other brand.