Client asked for a topsy turvy cake made of carrot cake. Carrot cake seems so like it is crumbly to me. Will it hold up if carved and stacked?

Personally, I won't do a carved cake out of carrot, especially one covered in fondant--too many lumps & bumps from raisins, nuts, etc.

I prefer a good, sturdy cake--poundcake-like--for topsy turvy cakes. They stand up to carving & gravity better.

JMHO
Rae

I've seen carrot cakes work great in topsy-turvy cakes. I've always found carrot cake to be more dense than crumbly. Any issues with bumps can be taken care of when coated with buttercream before adding fondant. Try working with it when the cake is frozen if you're worried about the crumb issue.