Chapter 1: Hand Block-Ins & Common Grips

Created by Sarah Choi (prompt writer using ChatGPT)

Hand Block‑Ins & Common Grips (Hold, Push, Pull)

For character concept artists across concepting and production. Focus: structure, gesture, and grips.

1) Why Hands Matter in Interaction Design

Hands are your character’s interface layer with the world. Solid block‑ins make silhouettes read at gameplay distance, while believable grips ensure props, weapons, and UI prompts feel grounded. Treat hands as mechanical-yet-expressive tools: they transmit force vectors (push, pull, hold) through the wrist and forearm; they also broadcast emotion through finger cascade, thumb posture, and tension.

2) Macro Structure & Proportion

Think of the hand as three coupled assemblies:

  1. Palm block (metacarpals) — a tapered wedge with a cupped concavity.
  2. Thumb module — a mobile clamp mounted on a carpometacarpal (CMC) saddle joint, independent axis set.
  3. Finger array — four hinged links with arcing knuckles and a natural finger cascade (index → longest middle → ring → shortest little).

Quick proportions (adult average):

  • Palm length ≈ middle finger length (base crease to tip).
  • Finger phalanges from base to tip ≈ proximal ~45%, middle ~35%, distal ~20% of finger length (varies per finger).
  • Knuckle arc: the MCP heads form a descending curve from index to little. The PIP and DIP arcs echo this rhythm.
  • Palm planes: a central flat flanked by two mobile pads — thenar (thumb mound) and hypothenar (pinky side) — creating a shallow trough toward the palm center.

Wrist/forearm:

  • Pronation/Supination rotates the radius over/under the ulna; the hand carries this rotation to tools.
  • Ulnar vs radial deviation bends the hand toward the pinky or thumb side; key in recoil and push mechanics.

3) Block‑In: From Boxes & Wedges to Fingers

Start with force‑aware primitives:

  • Palm: a tapered box (narrower at fingers), beveled at the hypothenar edge. Indicate the carpal heel as a short back bevel.
  • Thumb: a hinged wedge off the palm’s front‑side corner. Block as two segments: metacarpal (long wedge) and proximal phalanx (shorter wedge) ending in a nail cap.
  • Fingers: four three‑segment sticks (proximal, middle, distal) with blocky nails as orientation tabs. Stage the MCP knuckle line as a tilted arc.

Plane logic:

  • Dorsum (back of hand) is a broad plane that splits into tendons (EDC) toward the knuckles.
  • Palm is concave with transverse creases that articulate grasp — distal and proximal palmar creases; the thenar crease loops around the thumb.

Gesture first: establish line of action from forearm → wrist break → palm wedge → finger cascade. Let the thumb oppose or parallel the index to declare intent (hold vs point vs pinch).

4) Nail & Knuckle Landmarks That Keep You Honest

  • Nail plane tilts differently on each finger; its highlight sells finger rotation. Avoid pure white; it’s semi‑translucent with a brighter lunula.
  • MCP heads are offset — index sits forward of ring/little; use this to avoid flat, parallel fingers.
  • Web spaces (between fingers) form V notches dorsally and U folds palm‑side; they collapse in power grips.

5) Finger Cascade, Tension & Expressivity

Relaxed hands show a graduated curl: index least, little most. Tension straightens or over‑flexes joints depending on intent:

  • Aggression/push → extended MCP/PIP, thumb abducted (out), palm pronated.
  • Care/precision → gentle MCP flex, PIP/DIP fine arcs, thumb pad‑to‑pad contact.
  • Fear/withdraw → fingers cluster, thumb adducts, hypothenar folds in.

Design with offsets: staggered lengths, slight splay direction, and asymmetric thumb angles increase appeal.

6) Grip Taxonomy — Hold, Push, Pull

Below are production‑relevant grips, each described by contact patches, force vectors, and readability cues. Use these to align with animation, physics, and prop design.

6.1 Power (Cylindrical) Grip — Hold

Use: bats, hammers, sword hilts, thick handles. Contact: full palm wrap; fingers flex at MCP/PIP; thumb locks over index/middle or opposes around the handle. Vectors: force channels through thenar/hypothenar pads into the wrist; ulnar deviation common for strikes. Readability: closed finger silhouette, thumb either overwraps or meets index; knuckle arc visible. Keep the end cap of the handle clear.

6.2 Spherical Grip — Hold

Use: globes, knobs, magic orbs. Contact: finger tips and pads distribute on a sphere; palm forms a cupped bowl. Vectors: compressive toward center; wrist neutral or slight extension. Readability: gaps between fingers; thumb opposite the middle finger for balance.

6.3 Hook Grip — Pull

Use: bags, ledges, climbing, drawer pulls. Contact: fingers flex strongly at PIP/DIP; palm may not contact; thumb passive or assisting. Vectors: tensile load through flexor tendons; wrist ulnar deviation under load. Readability: hanging finger silhouettes; negative space under palm; forearm flexor definition.

6.4 Pinch (Pad‑to‑Pad / Tip‑to‑Tip) — Hold/Place

Use: beads, pages, tiny components. Contact: thumb pad to index/middle pad (or tips for delicate work). Vectors: minimal; micro control from intrinsic hand muscles; wrist neutral. Readability: small diamond of negative space; nails oppose; subtle compression of pads.

6.5 Lateral (Key) Grip — Hold/Push

Use: keys, thin cards, scalpel with side pinch. Contact: thumb pad presses object against lateral index. Vectors: shear force sideways; fine control from thumb adduction. Readability: object visible as a thin sliver between thumb and index; finger cascade relaxed.

6.6 Tripod (Pencil) Grip — Hold/Guide

Use: pens, brushes, stylus. Contact: thumb + index + middle form a tripod; ring/little provide ulnar support. Vectors: micro rotations at DIP/PIP; wrist slight extension. Readability: clear three‑point structure; tool angled ~45–70° to forearm.

6.7 Hammer/Overhand vs Underhand (Supinated) — Push/Pull/Strike

Use: melee, hammers, flashlights. Contact: power wrap as in 6.1. Vectors: overhand = pronation with downward push/strike; underhand = supination with upward pull/uppercut. Readability: forearm rotation visible at wrist; thumb position indicates over/underhand.

6.8 Pistol/Trigger Grip — Hold/Actuate

Use: firearms, sprayers, hair dryers. Contact: web between thumb/index seats the tang; middle/ring/little wrap; index isolates on trigger. Vectors: recoil through wrist extension; thumb safety/mag release motions. Readability: clear trigger finger isolation; avoid floating trigger—show distal pad contact.

6.9 Shield/Plate Push — Push

Use: doors, shields, heavy plates. Contact: heel of palm (thenar/hypothenar) with fingers splayed or braced. Vectors: compressive through extended arm; wrist slight extension. Readability: straight fingers with slight bend; strong palm plane to surface contact and a cast shadow.

6.10 Palmar Pinch (Jar Lid) — Push/Torque

Use: twisting lids/valves. Contact: all pads contact; thumb opposes across radius. Vectors: torque; forearm pronation/supination pair. Readability: spiral motion cues; asymmetric finger pressure indicated by whitening and crease depth.

6.11 Carry Grip (Suitcase/Brief Handle) — Pull/Hold

Use: rigid handles. Contact: power wrap with ulnar load; wrist slightly ulnar‑deviated. Vectors: tensile downward; shoulder compensates. Readability: vertical alignment of handle and forearm; slight finger blanching at contact.

6.12 Claw/Crimp (Climbing, Edge Pull) — Pull

Use: shallow edges, game ledges. Contact: fingertips only; PIP flexed, DIP hyperextended in crimp. Vectors: high tendon load; thumb may clamp over index for security. Readability: extreme fingertip emphasis; nails near edge plane.

7) Push vs Pull Language at a Glance

  • Push: extended MCPs, palm contact, thumb abducted, wrist extension; shoulder/torso lean forward. Cast shadows cluster under palm.
  • Pull: flexed fingers (PIP/DIP), palm hollowed, thumb adducted or locking; wrist flexion/ulnar deviation; back and biceps engagement visible. Design micro tells: blanching at pads, crease deepening, forearm tendon tension.

8) Hands + Props: Co‑Design for Readability

  • Handle diameters: adult comfort ≈ 30–40 mm for power grips; smaller for precision.
  • Edge breaks: chamfer edges where fingers seat; show wear/polish at high‑contact zones.
  • Guard/trigger reach: ensure index can reach without hyperextension.
  • Balance points: show center of mass with hand placement (further forward for control, backward for leverage).

Include prop orthos with hand silhouettes to verify grip logic for the team.

9) Production Handoff: Topology & Rig Notes

  • Deformation loops: maintain rings around MCP/PIP/DIP and a clean thumb CMC loop. Mark crease extents (palmar, thenar) for wrinkle maps.
  • Pose library: neutral, relaxed dangle, power wrap, pinch, hook, push‑palm, trigger. Provide min/med/max amplitude per pose.
  • LODs: preserve silhouette of knuckles and thumb web at low LOD; move vein/pore detail to normals.
  • Material IDs: dorsal skin (thinner), palmar skin (thick, matte), nail keratin, callus zones, glove materials if present.
  • Gloves: note stiffness and seam placement; gloves reduce crease depth and alter specularity.

10) Common Failure Modes & Fixes

  • Flat paddles: add palm bevels and a cupped concavity; show thenar/hypothenar mass.
  • Parallel fingers: restore knuckle arc and finger splay offsets.
  • Invisible thumb CMC: block the thumb as a separate module; show saddle joint offset.
  • Floating contact: add cast shadows/pressure blanch; align contact normals.
  • Trigger finger glued to guard: separate and stage the distal pad on trigger.
  • Wrist ignored: add pronation/supination and ulnar/radial deviations to sell force direction.

11) Gesture & Emotion Through Hands

Hands echo mood:

  • Open, upward palms — offering, trust.
  • Closed fists — tension, readiness.
  • Inward claw — fear, withdrawal.
  • Loose splay — relaxation, curiosity. Tie emotional beats to grip logic in storyboards so animation preserves intent.

12) Drills & Study Plans

Daily (15–25 min):

  • 5 palm‑box block‑ins from varied angles.
  • 3 thumb‑only studies (CMC to pad) in different oppositions.
  • 1 grip vignette (hold/push/pull) with cast shadow logic.

Weekly:

  • A grip sheet: power, pinch, hook, push‑palm, trigger, carry — each front/¾/profile.
  • One prop + hand co‑design page (handle options, diameter callouts, wear zones).

Monthly:

  • A pose library for your hero character: 12 hand poses with min/med/max, topology notes, and material IDs.

13) Checklists

Block‑In: palm wedge cupped • knuckle arc staged • finger cascade present • thumb module offset.

Grip: contact patch clear • force vector readable • wrist rotation aligned • pressure cues added.

Production: loops clean • crease extents annotated • LOD priorities defined • material IDs labeled • pose library delivered.

14) Closing

Design hands as force‑aware sculptures: start with a functional palm box, articulate the thumb module, lay in the finger cascade, and commit to contact/pressure logic. Whether your character is holding, pushing, or pulling, clear block‑ins and believable grips turn gestures into readable gameplay and memorable personality.