Hal Reynolds and I have been experimenting making trees using the Micro Mark twister pliers. These are easy to use and make nice looking trees and weeds.
Micro Mark sells what you need to get started - the pliers, wire and 2.5" strands of fur-like fibers. The pine tree with foliage is made using the Micro Mark products.
It took a little practice and we experimented with other materials. In the photo at the top of the page you see the pliers, a length of sisal rope and some wire from the craft store. The tree I made from sisal rope is the one without the foliage. It needs to be painted and then have dark green scenic foam sprinkled on.
The weed experiment is shown in the bottom two photos. This is just short lengths of rope fiber twisted into the wire. The strand was painted and placed in the scene - bottom photo.
If you're looking for a train-related activity while you're watching TV, making trees is the way to go. I never watch a ballgame unless I make a few trees!