I'm planning to create a large 3D wedding dress on a bust form cake for a competition.  I'm assuming it will be somewhere in the vicinity of 16" - 20" tall with a base of 16" wide.  What's the best process for stacking and carving something that high?  I've never attempted something that tall.  I am an experienced decorator seeking some opinions of stacking/carving methods.  I was thinking I'd stack 2 then add dowels and support then stack 2 more but then how will I carve the shape I need with the cake boards?  Any ideas?