Parametric OS-Railway Tracks - Straight

The rails I have made for my [models](https://www.thingiverse.com/thing:3106584) have generally been wooden which allowed me to make them much longer lengths than would be possible with my 3d printer. However on a couple of occasions I have designed and 3D printed some short rail lengths for displaying the models I have given to other people. Wooden rails are fine, even essential, for animation where long runs are necessary and fine detail isn’t. But for display, the 3D printed rails win with