The tracks I made using Romanjurt's flexible model were too fragile to survive playtime with the youngster. Especially the connectors. I needed something more durable. Atartanian's model seemed to fit the bill. I modified the model to work the same upside down since the youngin would accidentally place Romanjurt's tracks upside down and the train would derail. I also altered the dimensions to better match the Thomas Train tracks we have.
I've included the scad file but be warned I really butchered Atartanian's code with lazy hard-coded nonsense just to make it work. So changes might not yield the results you're expecting.