For a recent game I've been working with cheap plastic railway tracks, 2.4 cm gauge (made by Fenfa or other Chinese companies).
I cut the extremities and I quickly made a 6 mm thick polystyrene ballast and covered it with white wall coating. It still needs to be improved, I intended to glue decorative sand to look like ballast gravel ...but as the game was intended to take place on a snowy landscape I didn't do that yet; I'll probably do it later for other portions.

I still should reshape the extremities so they would fit better together.
The only slightly annoying thing is that I have too many curved tracks now, because miniature toy trains are intended to run on circular or oval layouts!


