You can download them from within Sketchup (there's a very large google repository of all sorts of objects) then export them and import them into your program of choice. However sometimes this is problematic and after messing around with it, I found it easier just to model them from scratch(in AutoCAD in my case).

Assuming you can extrude lines in solidworks? I can send you some files for supported rail and extrusion. What size extrusion?