How to Draw a Square Hole Optical Illusion
Learn to draw a convincing 3D square hole optical illusion on paper using basic perspective lines, careful value shading, and blending techniques.
- Read the tools, materials, safety notes, and steps below for free.
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🧰 Required Tools & Equipment
- ✓ Ruler (12-inch or 30 cm)
- ✓ HB Graphite pencil
- ✓ 2B or 4B Graphite pencil
- ✓ Blending stump (tortillon)
- ✓ Precision eraser or kneaded eraser
📦 Materials & Supplies
- ✓ Heavyweight white drawing paper (A4 or sketchbook)
- ✓ Scrap paper (for hand rest)
⚠️ Safety Checkpoints & Warnings
- • Keep hands clean and dry to avoid accidental graphite smearing across clean paper areas.
- • Use light pencil pressure to avoid tearing paper or scoring deep grooves into the surface.
📋 Step-by-Step Guide (6 Steps)
Draw the Outer Square Frame
Place the ruler in the center of the paper and draw a clean 10x10 cm square using the HB pencil. Keep your lines sharp, straight, and light so they can be adjusted if needed.
- • A centered, perfectly straight 10x10 cm square with right-angle corners.
- • Drawing freehand without a ruler, leading to uneven sides.
- • Pressing too hard with the pencil and creating deep paper grooves.
Plot the Inner Vanishing Square
Draw a smaller 4x4 cm square offset toward the top-right interior of the outer square. This smaller square serves as the deep bottom opening of the hole.
- • A smaller, neatly aligned square positioned inside the larger square toward the upper-right corner.
- • Centering the inner square completely, which removes the perspective angle.
- • Making the inner square rotated or skewed relative to the outer square.
Connect the Perspective Wall Lines
Using your ruler, draw straight connecting lines from each corner of the outer square to the matching corner of the inner square. These four lines define the receding interior walls of the drop.
- • Four distinct interior trapezoids formed by four diagonal lines joining matching corners.
- • Connecting mismatched corners (e.g., top-left to bottom-right).
- • Over-shooting line ends past the corner vertices.
Shade the Deepest Bottom Section
Fill the entire inner 4x4 cm square with your darkest pencil (4B or 2B) to create a solid black void. Lay down solid, consistent strokes so no white paper grain shows through.
- • An intensely dark, opaque square in the center-right representing infinite depth.
- • Leaving patchy light gaps or visible directional pencil strokes.
- • Smudging graphite into the neighboring wall sections.
Render Value Gradients on the Interior Walls
Shade the four side walls with smooth gradients ranging from dark near the inner square to lighter near the outer rim. Make the bottom and left walls significantly darker overall than the top and right walls to simulate a directional light source.
- • Smooth transitions from dark inside to light outside across all four angled interior wall panels.
- • Making all four walls the same uniform brightness.
- • Creating abrupt bands of tone instead of a smooth gradual fade.
Blend and Clean the Highlights
Smooth out the graphite gradients using a blending stump, moving in small circular motions along each wall panel. Finish by using a precision eraser to clean crisp, sharp white lines along the outer perimeter edges.
- • Velvety, seamless gradients with sharp, bright outer borders and high contrast against the dark center.
- • Dragging dark graphite from the inner square out into the lightest outer zones.
- • Blurring the crisp dividing lines between the separate wall panels.
Credit: inspired by an original tutorial by Jon Harris — watch the original on YouTube.
Don’t have everything?
- No Blending stump (tortillon)? Cotton swab (Q-tip) or folded tissue paper
- No 4B Graphite pencil? Standard #2 pencil pressed firmly for darker tones