Photo-montage
Kevin Poulton
Author made two photos of LEGO items and them combined them in Photoshop, obtained an impossble triangle.
You can see real LEGO constructions of impossible figures of other artists at the Sculptures section.
Artist's Redbubble profile http://www.redbubble.com/people/sadoldbiker
LEGO puzzle
The image was found at http://www.redbubble.com/people/sadoldbiker/art/4635444-3-lego-puzzle