re: Ben and Holly

Hi. Great cake!
I’m new to cake decorating and I’m attempting this cake. Can you tell me if you put any support structure in the outer castle (white) to support it while the icing was drying?
I didn’t use tylose as I was just experimenting, cut turret s in and had a guide of tin with baking paper on it. So I had sagging/gravitational shift downwards.
I can see how to do a few thing differently already but was hoping for some tips if you don’t mind.
Thanks