My nine year old daughter wanted a mad scientist party with an actual scientist cake and this is what I came up with. First I purchased a Bob The Builder pan. I used the pan as the shape for my scientist. I made a regular box cake mix in it and then attempted to decorate it differently.
I tried it first with a sample cake a week before the party to know how we would like it. I used a star tip for most of the cake, my daughter chose the colors. We gave him a lab coat, had him holding a test tube, gave him blue hair and a mustache, wearing thick black glasses, and a red bow tie. My daughter really liked the hair, blue is her favorite color.
I think this cake would like cute with gray or silver hair. This was a great hit at the party, and very different then usual science cakes.