Portal 2's unique aesthetic lends itself well to the world of toys, so I'm surprised we haven't seen a whole ton of such figures out there. This custom Atlas figure from Psychobob Arts is extremely well done (though not poseable, it seems).
The modeller himself has written up a lengthy post walking you through the process of creating this figure, from computer model to 3D printing to assembly. There are photos of each step for those interested in what goes into making awesome toys. I hope he makes a custom P-Body - it takes two to solve those puzzles after all.
From other sites around the web