Ink and pencil
Chris Tuckwell (herbevore)
Chris Tuckwell created two images with classic impossible figures. Derived from Reutersvärd's triangle, his version impossible triangle consists of cubes, which are decorated by knot designs in Keltic style. The impossible cube on the next artwork has even more complex decoration, because complex Keltic knot figure is divided among cubes of the impossible figure. So, every cube contains only small part of the big knot.
Artist's deviantART profile http://herbevore.deviantart.com
Knotwork block illusion
Image source http://herbevore.deviantart.com/art/knotwork-blocks-illusion-50032041
Image source http://herbevore.deviantart.com/art/Dice-Illusion-73842850