Homemade rail cars/trolley?
Old Man Dirt
Ingenuity! Real wheels like the railroads use are pretty heavy. But with a little creativity a lot of existing wheels used for other purposes can be modified to meet the need.
They buy wheels from a supply/hardware store or the internet and some, like miners, turn other things like metal pulleys or cloth spools into rail wheels. It takes a few hours for them to build the wheels into a whole chassis.