Photography: CC0 / Public Domain via Openverse.

metal lathe machining | cc0 | unknown | https://www.rawpixel.com/image/5940048/free-public-domain-cc0-photo
metal lathe machining | cc0 | unknown | https://www.rawpixel.com/image/5920838/photo-image-public-domain-free-metal
metal lathe machining | cc0 | unknown | https://www.rawpixel.com/image/6075509/metalworking-equipment
metal lathe machining | cc0 | unknown | https://www.rawpixel.com/image/6038472/drill-bit-closeup-free-public-domain-cc0-photo
metal lathe machining | cc0 | unknown | https://www.rawpixel.com/image/6064115/free-public-domain-cc0-photo
metal lathe machining | cc0 | unknown | https://www.rawpixel.com/image/5958541/free-public-domain-cc0-photo
micrometer caliper tool | cc0 | Internet Archive Book Images | https://commons.wikimedia.org/w/index.php?curid=167058736
drill bit macro | cc0 | Junkyardsparkle | https://commons.wikimedia.org/w/index.php?curid=27422229
drill bit macro | cc0 | Travis Soule | https://stocksnap.io/photo/macro-drill-Z39ZXFULBC
workshop tools bench | cc0 | Lisa Fotios | https://stocksnap.io/photo/workbench-machinery-RKR8CFTODQ
workshop tools bench | cc0 | The World is a Stage | https://stocksnap.io/photo/workshop-wrench-O8DVPXYOIY
workshop tools bench | cc0 | Flat Lay Photos | https://stocksnap.io/photo/workshop-wrench-SM72VGLBBK
workshop tools bench | cc0 | unknown | https://www.rawpixel.com/image/13993827/image-cartoon-person-sword
Code libraries: motion.min.js = Motion v12 (motion.dev), MIT license, vendored locally.

Derived images (processed for this study):
drills-alpha.webp = drills-yellow.webp with the yellow ground removed to alpha
  (deterministic border-connected flood fill, Python/PIL). Same CC0 source as above.
paper.webp = procedural paper texture tile generated for this study (Python/PIL,
  seeded noise). Not a photograph. CC0.
drill-seq/ = 36-frame rotation film of a two-flute twist drill, modeled and
  rendered in Blender for this study (headless, procedural geometry).
  Original work, no external assets. CC0.