Marshmallow fondant decorations on Wilton Whipped Icing Mix. Would not use the whipped icing mix again! I tried to take the easy way out having a newborn and making this cake for my 3 year old, but it was very soft and hard to make look nice like homemade buttercream. The Thomas train is a toy. I didn't have enough time or energy to try to make my own! :) I got ideas for the track coming out of the tunnel and carving the cake from other cakes here on Cake Central!