This is the MakerSlide extrusion by Bart Dring http://www.thingiverse.com/bdring from http://www.makerslide.com/.
MakerSlide is a V rail integrated into a standard aluminum extrusion profile. It's going to make designing light-duty CNC systems easier and more affordable.
I've just put the design in a few different formats, so we can start to use it in free software.
OpenSCAD + DXF
makerslide_extrusion_profile.dxf : The first step was to bring the published DXF into Blender, convert into millimeters (1 Blender unit == 1 mm), and place it at the origin in a way that will be easy to work with when trying to do translate() calculations in your head, for OpenSCAD.
makerslide.scad : This OpenSCAD script just demonstrates using the built-in DXF import-and-extrude function, wrapped in a module, so you can start using makerslide(h) whenever you need to stick a linear slide somewhere. (Make sure makerslide_extrusion_profile.dxf is in the same directory as the OpenSCAD script.)
vwheel.scad : model of the delrin V wheel from the drawings for bdring's version 2.0 laser http://www.buildlog.net/sm_laser/drawings.html
makerslide_2D.blend : This is the Blender file I used to make the DXF. (Though I changed the layer name in the DXF source to "makerslide".)
makerslide_3D.blend : 100mm extrusion as a mesh in Blender.
vwheel.blend : delrin V wheel, with bearing, as mesh in Blender.
makerslide_100mm.skp : 100mm extrusion and one v wheel in Sketchup.
There is another "dynamic" (parametric length) version of this by Meduza done in Sketchup Pro. Find it in the Sketchup 3D Warehouse, here:
... but no wheel. So check Meduza's model to see if it's easier to work with, and then get the wheel out of my model.