Ink and pencil
Dubious Duo (Arty-Rile-Ditch)
A pencil sketch of a very interconnected structure, which is based on impossible triangle.
Artist's deviantART proifle http://arty-rile-ditch.deviantart.com
The image was found at http://arty-rile-ditch.deviantart.com/art/Mobius-strip-116574215