I made my first carved / 3D cake last night. It's in the shape of a motorcycle gas tank. I had a really hard time figuring out what to do with the board that sits directly under the cake - not the decorated big board, but the little cardboard that enables you to move it around. I wound up cutting the board with an exacto knife after the cake was carved, but I was thinking there has to be a better way. Do you cut the board before you carve the cake - I don't see that working either? How do you do this?

It's not done yet - missing name plate on the front, but here's the almost finished cake.

I usually know exactly what size my finished product will be, so I cut that board to measure before I carve.