[Russel Munro] decided to go all-out for his son’s birthday cake: he made a Transformers robot cake that, well, transforms from a truck into a robot, Optimus Prime style. His impressive build has the actions of the original: first, the front rears up to lift the head, then the back lifts to form the body and the head and arms pop out of the top. Underneath the thin fondant exterior is a 3D printed body, driven by a mechanism in the base. He used fishing line to lift the parts, which is pulled by a motor salvaged from a CD player, being driven by an EasyDriver board from Sparkfun.
The main issue he had to overcome was weight: apparently he underestimated the weight of the fondant that covers the cake, and had to do some last-minute work to strengthen the drive mechanism, and skip plans for the more ornately decorated version that his wife had planned. But the look of glee on his son’s face when he operates it at the party is the best bit. In these days of CGI and computer games, it is good to remind the kids that there is still a lot of fun to be found in ingenuity and liberal quantities of hot glue.