Between the Lines, subtitled an “Expert Level Coloring Book,” is impossible to color properly with crayons.

Filled with intricately detailed lined drawings, you’re going to need steady hands and some finely-sharpened colored pencils to properly do the trick. Illustrated by Peter Deligdisch, the book contains a variety of artwork. [E]ach illustration is filled with a ridiculous amount of detail, making the job of laying down color feel like solving a complicated maze.

Via CoolThings.
Between the Lines: An Expert Level Coloring Book available on Amazon.