When Kai was much younger, I would draw train tracks on the back of restaurant menus sometimes when we travel or when we eat out, so Kai can place his trains on them. This is much easier than carrying actual (Thomas) train tracks everywhere and I can draw whatever scenery he wishes.
So now, he draws train tracks on his own^. It's a small feat to adults. But we are bursting with pride as he's able to draw straight lines!