Thanks for the suggestions and compliments! I actually did use fresh fondant, made it just a few hours before. Actually it didn't really crack, I put lines in it to look like the metal reel. However, when I covered the boards the cardboard edge cut into the fondant (probably it was too thin, but I figured why waste a thick layer on fondant on a board, and risk getting random dents in it) and made it break off. So you can see the corrugated board in some places, not in other. Next time I will have a different plan!