Every Finger Gets a Line
An industrial-design interaction study — hands operating one product, drawn in pen line — sized and separated so the hands survive being the subject. Six fields.
Two runs of the same template. A palm-sized picker beside a handheld radio — five grips each, fingers countable in every vignette of both. The radio run draws more of the product body than the template asks for and adds a belt and trousers for the clip action, where the picker run keeps to the touched parts only. The looser reading still holds the rule that matters.
Generated from this template with the fields shown above — five grips, overlapping rather than gridded, and four fingers and a thumb countable in every one of them including the smallest. Nails, knuckle turns and the separating contour where one finger passes another are all present. The reference's baseline is why the count came down from eight to five. Its large central hand was genuinely good, and its small ones, crowded into the lower edge, had fingers merged into a single undifferentiated mass. The drawing did not fail at random: it failed wherever the hand was small, which makes size a rule rather than a hope. The line idiom is doing quiet work too — confident contour absorbs errors that smooth rendering exposes, which is why this subject survives here and wrecked the 3D character baseline elsewhere in this library. This pair is the second attempt, and the reason is the most useful thing in this entry. The first pair shipped with a six-digit hand in the top-left vignette — an extra finger above the four and the thumb — and merged digits in another. I had reported that pair as passing, having counted fingers on a downscaled two-panel review sheet at a size where counting was not actually possible. The defect was caught by a reader looking at the published card. What fixed it was an explicit count rule that overrides the rest of the template, and the instruction to draw fewer visible digits rather than pad a hidden cluster, since a half-drawn group is exactly where a sixth finger appears. Three vignettes still separate their curled fingers with hatching rather than clean contours, which is partial compliance with the separation rule and is left recorded rather than reshot.
Generated for this library
Input
Object a handheld colour picker - a palm-sized puck with
a lens on its underside
Actions press flat against a surface · thumb the capture
button · twist the collar · slide the lens cover
open · lift away between finger and thumb
Hero thumbing the capture button, about a third of the
page height
Drawn only the top face, collar and lens rim
Arrows the twist and the slide, one each
Paper warm white stock, fine black technical pen
Returned 1 sheet · 3:4 · pen line, no colour, no text
layout five vignettes overlapping and interlocking rather
than gridded, the hero at centre left
hands every one large enough to count fingers, each finger
separated by its own contour where they overlap
line heavy confident outlines, finer interior structure,
a few restrained hatch strokes for occlusion only
product cropped to the parts being touched, everything else
left off the page
arrows two only, thin, following the actual motion pathYou fill in 6 fields — the braced lines at the top. Everything below them is fixed.
- 1The object being operated
- 2Five actions
- 3The hero action, drawn largest
- 4What of the object is drawn
- 5Which actions get a motion arrow
- 6The paper and pen
Every Finger Gets a Line
Produce ONE image, 3:4 portrait: an industrial-design interaction study sheet in pen line. Follow every line. Replace only the FIELDS block; everything after it is fixed.
First — do you have the fields?
If any field below still has braces around it, stop and ask. Put all the questions in one short message, and show the example under each one so they can see the shape of a useful answer. Wait for the replies, then draw. Never fill a brace yourself: a value you invented is a value nobody asked for, and it will look exactly as considered as the ones they did give you.
Ask in whatever language they are writing to you in. Translate the questions and the examples; do not make someone read English to tell you what they want.
The examples are only examples. If someone answers a question, use their answer; never fall back to the example because you prefer it.
If the fields are already filled in, ignore this and carry on.
Fields — replace these six lines only
- The object being operated: {what it is} e.g. a handheld colour picker — a palm-sized puck with a lens on its underside
- Five actions: {five different grips, each naming the part touched} e.g. press it flat against a surface, one hand · thumb the capture button on top · twist the collar to change mode · slide the lens cover open · lift it away between finger and thumb
- The hero action, drawn largest: {which one, and how large} e.g. thumbing the capture button, at roughly a third of the page height
- What of the object is drawn: {only the touched parts} e.g. only the puck's top face, collar and lens rim — no back, no branding, no full body
- Which actions get a motion arrow: {one or two} e.g. the twist and the slide, one arrow each
- The paper and pen: {a stock, and a pen} e.g. warm white stock, fine black technical pen
The size law
Hands are the hardest thing to draw and they fail in a predictable way: fidelity scales with how much room the hand is given.
A reference run of this style was asked for eight interactions on one page. Its large central hand was genuinely good — knuckles, nail, joint turns, foreshortening all correct. Its small ones, crowded into the lower edge, had fingers merged into a single undifferentiated mass. The drawing did not fail randomly; it failed wherever the hand was small.
So:
- Five actions, not eight.
- The hero is roughly a third of the page height.
- No vignette is smaller than a sixth of the page height. If five will not fit at that size, draw four.
The separation law
This is the specific failure, and it is checkable.
No two fingers may share a silhouette without a line between them. Wherever one finger passes in front of another, there is a visible contour separating them. Wherever fingers lie side by side, there is a gap or a crease line. A hand whose fingers dissolve into one shape at the knuckles has stopped being a hand.
Draw, in every vignette: the palm or back, the wrist, the thumb, the four fingers with visible joints, the nail on any finger seen from above, and the turn of each knuckle.
Count the digits
Every hand has exactly five digits: one thumb and four fingers. Count them on each hand before finishing it. If the count is not five, redraw that hand with fewer.
Where digits are hidden behind the product, draw fewer visible digits rather than adding extra ones to fill the space. Two or three fingers shown clearly beats five shown ambiguously — a half-drawn cluster is where the sixth finger comes from.
No finger forks, branches or sprouts a second tip. No nail appears without a whole finger attached to it.
Check the smallest vignette first, at full size. If four fingers and a thumb cannot be counted in it, the page has too many actions. Checking this on a shrunken contact sheet is not checking it: the first pair of runs from this template shipped with a six-digit hand that a downscaled review missed entirely.
The line
Pure contour drawing. This idiom is what carries hands — smooth rendering exposes every error, while confident line absorbs it.
- Outer contours heavy, stable and certain, drawn with long unbroken strokes. No sketchy repetition, no feathered searching lines, no wobble.
- Interior structure finer, and much sparser.
- Hatching only where one form occludes another, a few strokes at a time. No broad shading, no tonal modelling, no fill.
- Nothing in colour. Nothing rendered.
The composition
Not a grid and not cards. The vignettes overlap, interlock and sit at slightly different angles, filling the sheet densely with no ruled divisions and no boxes. The hero anchors it; the others crowd around and partly behind it.
The product
Draw only the parts being touched — the button, the collar, the edge, the lever. No full product views, no back faces, no branding, no logos. The hand is the subject and the object is context.
Never
- ✕ more than five actions
- ✕ a vignette too small to count fingers in
- ✕ fingers merging into one mass at any overlap
- ✕ a hand with more than five digits, or a nail with no finger
- ✕ cartoon hands, mannequin hands, or anatomical-diagram hands
- ✕ colour, marker rendering, 3D, or photographic reference
- ✕ any text, number, label, dimension or annotation
- ✕ boxes, rules, or a gridded layout
The result
A page that reads as a designer's own working sheet: five real grips on one object, drawn large enough to be believed, in line confident enough to carry them.
A note on the companion rule
Another skill in this library takes the opposite position — it keeps hands out of frame entirely, because in a character portrait they are an incidental risk with nothing to gain. Both are right. When hands are not the subject, design them out. When they *are* the subject, give them size, draw them in line, and separate every finger.
The whole template, in one piece. The steps below are the entire workflow.
How to use it
- Copy the whole template with the button above.
- Replace the six FIELDS lines. Write five genuinely different grips — a press, a twist, a pinch, a slide, a lift — not five views of the same hold.
- Paste it into any image-capable agent or model, in one message. One run returns the sheet.
- Check the smallest vignette first, not the biggest. That is where fingers merge, and if you cannot count four fingers and a thumb in it, the sheet needs fewer actions rather than better ones.
What you swap
- The object being operated
- a handheld colour picker — a palm-sized puck with a lens on its underside
- Five actions
- press it flat against a surface, one hand · thumb the capture button on top · twist the collar to change mode · slide the lens cover open · lift it away between finger and thumb
- The hero action, drawn largest
- thumbing the capture button, at roughly a third of the page height
- What of the object is drawn
- only the puck's top face, collar and lens rim — no back, no branding, no full body
- Which actions get a motion arrow
- the twist and the slide, one arrow each
- The paper and pen
- warm white stock, fine black technical pen
Before it runs
- A product people touch in more than one way. A thing with a single button gives four repeats of the same drawing.
- Acceptance that the hand outranks the product. These pages are about the grip; the object is context and is drawn as little as possible.
- Restraint about the count. Adding a sixth or seventh action is exactly how this sheet turns into merged fingers.
When to reach for it
When a product has to be shown being used rather than admired: an ergonomics study, a patent-style sheet, a design review page. Templates in this style ask for eight interactions on one page, which is exactly the count at which hands stop being drawable.
What changes
- One dense pen-line study sheet: overlapping vignettes of hands operating a single product, no text anywhere.
- Five actions rather than eight, because hand fidelity scales with how much room a hand is given and the small ones are where fingers merge.
- A size floor on the smallest vignette, so every hand on the page is big enough to show individual fingers.
- A separation rule — no two fingers may share a silhouette without a line between them — which is the specific way these drawings fail.
- Pure contour line with no blended shading, the idiom that carries hands where smooth rendering exposes them.
Pairs with
- One Object, Two StatesAn industrial-design sheet for a translucent ribbed product, shown closed and open — with the two views held to being the same object and the size stated on the page. Six fields.
- The Shaft Runs the Whole WayAn exploded product view on white — parts strung along one axis in assembly order, with anything that passes through drawn long enough to reach everything it passes through. Five fields.
- Count Both SidesA value-proposition canvas — a square facing a circle, three regions each — where the two halves are written as pairs, so anything unmatched shows up instead of hiding in a list. Six fields.