Can anyone give me tips on how to attach panels to each side of a square buttercream covered cake? When cutting the panels down to size, won't they snap off / crack? Does anyone know of a useful link to show how to do this?

I don't know if I will be helpful in this, as I never done it before, but yesterday I watched Amazing wedding cakes in TV, and they pre-chill the panels before putting them on a side of the cake. That way it will stay in a shape you cut.

I wouldn't cut it off when it is already dry and hard.