A cookie "sushi" project I did for Christmas, inspired by these sites:
I made the tobiko by dyeing sugar--put some sugar in a ziploc bag and gradually knead in food coloring. I used turbinado sugar to get a larger texture. I would have used nonpareils if I could have found them in orange.
I made the orange gummi mixture using the first recipe here: answers.yahoo.com/question/index?qid=20060906 114646AAL9gA7. It was pretty easy--basically just melting gelatin and water together. I then put the mixture in a squeeze bottle (mine is a Wilton brand bottle) and just squeezed out a bunch of dots on parchment paper. They solidified pretty quickly, retained some slight roundness, and then I had the tedious task of putting them all right side up on the Rice Krispie treats. :) They did harden within about a day unfortunately, maybe because of their small size.
For the seaweed, I made chocolate "plastic" from dark chocolate, black food coloring, and corn syrup: allrecipes.com/Recipe/Plastic-Chocolate/Detai l.aspx. The corn syrup made it so I could roll out and shape the chocolate. I tried chocolate plastic in the "California rolls", but it was more tedious and was also thicker than just brushing melted chocolate on the Rice Krispie layer. Both sort of oozed into the other layers, so I would like to find another source of thin black stuff, besides nori itself. :)