Edit July 13th 2016: Added a 2 1/2" version of the spacer to allow for proper NMRA spacing around turns. All other features are identical.
It's the little things with 3D printing. This morning I was working on my train layout for the first time in months, and needed a few track spacers for the mainline in the center. The tracks needed to be exactly 2 inches apart to meet the Free-Mo specifications. In order to achieve this, I took a few basic measurements and created this spacer. The spacer is set to hold most brands of manufactured track (I tested it with Micro Engineering flex track, Atlas flex track, and Atlas snap track) at a 2 inch on center spacing. There is a hole in the center of the jig to allow for a screw to be temporarily used to hold the track in place while the nails are driven or while glue is setting (glue is preferred in my case).
No recommendations in terms of print quality or speed. The edges are rounded to help provide smoother printing, especially on my older PB LCv2. Happy Modeling!