Calligrapher Mario Bono recently alerted me to a great article over on CoDesign

I have often said designers and printmakers working with physical type preform mental gymnastics (working upside down and back to front with text). The ultimate mental acrobat was of course MC Escher. His art was the inspiration for Oxymora - a typeface made entirely of impossible geometric shapes.
Like Escher's work, the longer you look at it, the more your mind lurches as you try to wrap your head around what you're seeing.

Designed by Barcelona-based illustrator and multimedia designer Birgit Palma. It's an innovative and exciting take on the geometry of letterforms.

“The Escher-esque feel of the typeface is no coincidence. "A little while ago, I did some work for a client and started to play around with Escher's impossible shapes," Palma told Inspiration Hut. "In the end I got so addicted by the system that I made a complete font, based on impossible shapes."