Is the egg breaker your original design Nick?
The hammer was a double hammer from Märklin Metallbaukasten book, I added a bunch of extra pieces to fasten it to the engine, but two hammers was too much for the little engine. I built it around Easter time so the egg breaking idea came to me and I slightly modified it a little more

The kids thought the eggs were a little crunchy but that’s because they kept hammering till some shell was embedded into the white 😂