Envelope/block-in

Reducing a subject to a few straight-edged shapes so you can lock in proportion, tilt, and placement before adding detail.

What it is

Envelope or block-in traps the subject inside a simple, angular cage of straight lines. Skip detail and curves and ask only: what is the outermost boundary, and where are the big angle changes that define it? Lay down those few lines first, lightly, to claim the space on the page.

With the envelope in place, subdivide it into smaller blocks, still using straight lines, to place major features: head and torso masses, light/dark divisions, big folds, silhouette breaks. Save curves for later — at this stage, approximate everything with short, straight angles.

In practice, start a figure or object with a 6–12 line polygon instead of a contour drawing. Step back, check those angles and distances, and adjust until the block feels solid and balanced on the page — only then move to more specific shapes and interior structure.

Why it matters

Without an envelope, drawings drift as you chase one detail after another: features end up misspaced, tilts go off, and the figure stops fitting the page. A block-in gives you one simple structure to measure against, so you catch errors early while lines are still simple — making drawings more accurate and easier to keep consistent across a page or project.

You can check it when

• ✓You can start a drawing with 6–12 straight lines that convincingly capture the subject's outer shape and tilt before adding curves or detail.
• ✓Your finished drawings match your initial envelope closely — you're not constantly erasing and expanding past that first big shape.
• ✓You can quickly block in moving or complex subjects, like a figure in motion, so the envelope still reads as the right pose and proportion.
• ✓Your proportions are more accurate when you block in with straight lines first than when you start by drawing outlines or details directly.

Related skills

• Measurement (comparative, angles, plumb lines)
• Accurate proportion — including correcting errors mid-drawing
• Shape simplification
• Primitive forms in any rotation (boxes, cylinders, spheres and modified spheres, cones, pyramids)
• Basic mannequin
• Boxes in perspective (above/below eye level, rotated)
• Thumbnailing (multiple variations, simplification, reading at thumbnail scale)