Your grandson must have loved that birthdayCool. I like it.
A few years ago we made a rocket-themed birthday cake for our grandson. I built a flyable Mosquito and we mounted it on the cake using a bamboo skewer glued to a JT-5C. The skewer was then covered in frosting to look like the exhaust plume from the rocket.
After removing a bit of frosting from the Mosquito we got a chance to fly it.....I think it got four flights before it went the way of most Mosquitos and disappeared.