I am a level designer for the Source engine. I am currently working on a couple of mods, including the remake Black Ops:Source. Since I have been working with the Source engine for about 3 years now, I know most of the tricks and loopholes of level design. If you have any problems with hammer, let me know and I'll do my best to help you out.
Designed in Blender (v. 2.59)
Total design time: around 5 hours
Vertices count: 2649
Face count (quads): 2816
It's still in development, but it's nearing completion. I've listed all of the faults I've found with the model on the top picture. The full render is the one below.