For my sushi cupcakes I made mini cupcakes and made sure that they didn't have much of a top on them. then I just bought some supplies and candies to arrange my sushi. Here is a list of the supplies I purchased:
black cupcake liners
white oblong sprinkles to look like icing
orange tic tacs for "fish egg" sushi (orange jelly beans would work better but couldn't find any
candy orange slices
candy fish for the ones on the end
fruit roll up by the foot
Then I just made a variety so it looked like we had a variety of rolls. They were a lot of fun and really good. Cake and candy.. doesn't get better then that!
Just let your imagination run wild!!!!