When done here the members made their own. One laid out everything in carboard. With a pencil and string you can draw out templates on cardboard and use those as guides. After doing my loop I wish I had used a straight edge. The curves came out even because the brass resisted every twist. Don't know of any commercially available.
Are you talking about a rail laying guide for laying rail by hand? I've been in this hobby a long time and have never seen, nor heard of, a flex track template. But, then again, I may have been living a sheltered life.......
err, isn't the point of flex track is to conform to exact desired shape?
why would you need template? does it really matter if its 23.5R, 26.7"R or 24.25R ? you draw what fits in your given space and then just lay it down.