The Castle cake from hell - uses a kit to add the turrets etc but it was horribly difficult to keep the turrets from falling over. And icing plastic is not as easy as I thought! The cake itself was white chocolate mud cake with white chocolate ganache icing.
Rainbow cake - had to colour sugar (stick sugar in a bag with food colouring and shake) then pour in lines. With my shaky hands there was no chance that the lines would be straight! The clouds are fairy floss.