How to render an object as a transparent wireframe? I'm a psychology student (and 3D design noob) who's been tasked with designing items for a test of spatial ability like this example... 



I've been playing around with Blender, and I've gotten this far...


So the shapes I want are there, but I'm having trouble getting out rendered on white with black outlines.

I tried changing the World Horizon Color to white, which fixes the background, but the cube object renders solid. Any ideas on how to get it outlined like in the example?

P.S. That "LS" in the example is meant to be a window. Any suggestions on how to accomplish that would also be wonderful; I haven't even attempted it yet.
One way you could do this is by using freestyle:




Create a transparent material and assign it to your objects:


Enable freestyle in Render settings:


In Render layers, set the line visibility to QI range and set the end to 1:



Think of the QI range like a sort of depth index; faces directly visible to the camera are 0, faces behind those faces are 1, faces behind those faces are 2, etc.

By only rendering lines on faces between 0 and 1 (inclusive), you can get a result like in your example image.




Or you could use wireframe materials:



See this question for details.