Whilst in San Francisco I made a spectrum cake to look like the Apple Mac "spinning wheel of doom" icon with a rainbow of layers in the same colours as their logo. It took an evening of mixing and individually baking each sponge and then a morning of mixing and spreading icing to build the tower block! Here are all the stages and the final assembly with icing on the whole exterior and sugar crystals to make the wheel pattern.
My blog has just hit it's 10th birthday so I'll dedicate this entry to such an auspicious anniversary!
Find the recipe I followed for quantities and method here.................. albeit without the pink layer because there's no pink in the Apple logo. Thank God because I don't think it could have got any higher!