Tool recommendation needed

[wachuko]

I don't understand this photo View attachment 420285. The colored area where the wheels run appears to be added on or has it just been colored manually?

That was me... visualizing/finding the anvil inside the railroad track... That is how I initially intended to machine it. Removing everything that is green.... With feedback from the folks here in the forum, I decided to leave one side curved and the other one sharp. That was a great idea as it has come handy in a few occasions...

Here... photos should help with what I am trying to say...