@thecakeo , some people do it, but I have had no luck carving a dummy. I have carved and shaped florist's oasis for medium sized figures, but no luck at all with regular styrofoam. I believe some sort of heated wire is used.
Not long ago, I remember seeing a discussion about a company that would make custom dummies and I believe it was in the UK. Maybe a Google search will turn up something.
I have found it to be difficult and very messy but it can be done. It does depend on how intricate you want the carving - what are you hoping to make? Maybe it would be easier to use rice cereal treats? I be that would crave easier (but I have not tried it.)
Once again, @kakeladi , you are a genius! I've used Rice Krispies Treats many, many times and they carve beautifully. One trick is to process the Rice Krispies in a food processor to break them up before mixing them with the melted marshmallows. That way you are able to get a more compact, dense shape, making it easier to carve. It also helps to eliminate the butter when making RKT's for carving and molding.
oh i LOVE to carve foam -- i've done it both ways -- with the heated cutters and cold turkey --
if you use a knife -- just go outside because it can get messy -- i've made fluted tiers and teeny tiny tiers and lots of plateaus and tons of regular tiers --
oh yeah -- you sure can -- go for it -- 
oh yeah -- you can go to the big hardware stores and buy sheets of insulation made of foam and dudette, you are in foam freaking heaven -- i love to sculpt foam and cake -- love. it.
if you decide to go this way -- lookie what i found
http://www.ema-models.co.uk/index.php/power-tools/hot-wire-cutters/hot-wire-foam-factory.html
I can't make heads or tails of that thing (hot cutter), @-K8memphis ! I am bringing myself to Memphis and beg you to give me styrofoam cutting lessons! I have carved it with a knife (OUTSIDE) and made the biggest d..n mess you've ever seen. It was stuck in my hair, on my clothes, on my hands...everywhere! There are probably still styrofoam balls floating around my yard! I am talking about the kind of styrofoam that cake dummies are made of. Never thought about foam insulation, which is a dream to cut and I even have some in the basement!
come on down -- i'm working hard on my degree in curmudgeonism but i could fit in a foam lesson -- gawd -- i'd have to clean my house first ha!
yeah, i've cut all kinds --i still have it in my backyard too -- kind of like permanent snow -- big fat grin -- neighbors pass back & forth watching the progress --- what is she doing now? ha!
Thanks everyone I've only just got this and don to know how to reply to everyone individually. I will be using rice crispy I am doing a farm land wonderland for the under 18 decorative exhibition (am 13) I currently can't afford hot wires and probably won't use them after this so it's not a good investment. If you want to see some of my creations I am on instagram @thecakeo. Again thank you all.
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