Pencil lines drawn evenly across a sheet of plain paper are crossed with two parallel vertical lines. This defines the outer edge of the 3D hole in your paper.
Erase the lines inside that box, as well as the left vertical line, then draw diagonal lines as shown. With some specific shading and a turn of the paper, a 3D hole is created.
How can lined paper help create the 3D illusion? In this wordless Circle Line Art School video, the paper’s lines are a guide for drawing a niche in the paper. A few diagonal lines and some shading builds the effect.
Level up with these illusion videos on TKSST next:
• How to draw a cubetacular hole in your paper
• How to Draw a 3D City: Line Paper Anamorphic Drawing
• The mathematics of sidewalk illusions