I have a Silhouette – not the Cameo but the slightly older model. I have only ever used it for non-food things (paper, card and other crafts) – never for my cakes.
I’ve had it for a while and my memory is failing me a little, but I’m sure I looked into it at some stage, and discovered it wouldn’t work for cake decorations – I can’t remember where I got my information from but I’ll have another search and come back to you.
For cutting paper, however, I love it.
