Stockton and Darlington Railway
https://en.wikipedia.org/wiki/Stockton_and_Darlington_Railway
This is a model of the early Stockton and Darlington railway Chaldron wagon. It is based on the images of a wagon in the The National Railway Museum at Shildon catalog number:
The parts are called 'Active' because that was the locomotives original name. Michael Bailey's report is here: https://www.railwaymuseum.org.uk/sites/default/files/2023-10/Pages%20from%20LOCOMOTION%20report%20part%201.pdf
The files contained here are experimental and have been made available for development purposes only. There is not yet sufficient to make a complete locomotive.