Next anticipated question,how to finish them ?
There are a few different options,some companies produce a Blackener thst weathers them,it could be tricky to use as the tracks need to be thoroughly cleaned,I scrub them with a toothbrush and acetone,if they are not cleaned right the process wont work.Some weather individual links,some assemble and weather.There are also a lot of homemade brews and alternatives that I have not tried,but if done right they look good. Then add washes and pigments.
I have also painted Fruils with regular paint,washing,and weathering with good success.
With either method you have the option of sanding the wear areas to expose bare metal to simulate wear.
They are fun,look great if done right,but not cheap.
There are a few other metal track companies,used to use Spade Ace,also Master Club.
Have fun sir