I saw this toy in Landskrona museum sweden. It was i guess around 100 years old. I liked it and made this design. It is not the same with the toy in museum, this is quite a new design. But everything is tested and simulated in solidworks. It will run nice.
I'm updating this design from time to time, visit endtas.com/mechanical-horse-toy/#more-248 for the latest STL files.