Modelkasten is my prefered brand of aftermarket tracks, and eventhough i live in europe i sometimes order from RZM aswell, they have reasonable prices and excellent service.
But be careful with modelkasten tracks, they are fragile let there be no question about that, but if done properly they can take some handling and look amazing, i did a tutorial for Modelkasten Tiger I tracks a while back maybe you can find some helpful hints.
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