These are some very simple dev textures I produced in my spare time due to sheer boredom (I need to get out more). Basically, they are some very basic shades of gray, including a black and white version of the three main wall and floor textures.

I have to give some credit to the TF2 mapping forums somewhere on the internet, as they provided a very very helpful template. And some credit the guys at http://nemesis.thewavelength.net/ for the VTFEdit tool I used to get them into the game.