I made a groom's cake for an awesome couple last weekend. They were both self-professed "computer geeks". They wanted the groom's cake to match the wedding cake's colors. They decided on retro circles and an argyle pattern.
For the argyle tier, I measured the height and width of my middle tier and then used Microsoft Powerpoint to make a custom harlequin diamond template. I do this a lot, especially when I want a very precise fit. For the "stripes", I wanted them to be very thin, and very unobtrusive. I wound up cutting thin strips off of edible image paper and then painting them with silver luster dust.
But I almost forgot about the best part of this cake, and I had nothing to do with it!! The bride and groom (the self-professed computer geeks) made their own wedding topper. Didn't they do a great job? The french cuffs, the lacy bodice, it's all just so cute and wonderful.