Cake Projector Alternatives
That is totally doable. Just print out an appropriately sized copy of the desired picture and put a piece of waxed paper over it. Using a piping bag, trace the picture with frosting, filling it in. Then freeze the frosting and waxed paper. Once it is frozen, peel away the waxed paper, and put the pieces on the cake.

Here is a great pictorial of the process.