fabrication
Rapid prototyping: 3D-printed replacement faces
Replacement face systems
Definition
Rapid prototyping is the fabrication process, pioneered by LAIKA starting with Coraline (2009), of building a puppet's replacement-face library as full-colour 3D-printed parts instead of hand-sculpted resin or foam-latex pieces. An animator's digital sculpt of a single expression is sent straight to a 3D printer, which outputs a finished, ready-to-shoot face part with no hand-carving step in between -- letting a studio manufacture and swap far more distinct expressions than hand fabrication alone could sustain on a feature's schedule.
Overview
Replacement face systems are as old as the Puppetoons, but the fabrication step -- carving, casting or hand-sculpting each expression -- has always been the bottleneck (see replacement-face-systems). LAIKA broke that bottleneck starting with Coraline (2009) by moving fabrication itself onto a 3D printer: an animator's digital sculpt of a single expression goes straight to a rapid-prototyping (RP) machine, which prints a finished, full-colour, ready-to-shoot face part with no hand-carving in between. Brian McLean, LAIKA's director of rapid prototyping, later described the idea as one the studio had been chasing for "over a decade" before it became, in his own words, "a groundbreaking process that has forever changed stop motion animation filmmaking."
The printers changed faster than the underlying idea. LAIKA's early films used an Objet Connex3, the first printer capable of producing the coloured plastic the studio needed at all; by Kubo and the Two Strings (2016) it had moved to a Stratasys J750, a full-colour, multi-material printer offering roughly 360,000 base colour combinations, later extended further by Stratasys's Voxel Print software for finer textures and gradients. According to Stratasys's own case study, the number of physical face pieces printed climbed with every film: about 20,000 for Coraline, 40,000 for ParaNorman (2012), 56,000 for The Boxtrolls (2014) and 64,000 for Kubo and the Two Strings, with LAIKA's fifth feature, Missing Link (2019), reported at 85,000-90,000.
A printed-part count is not the same thing as an expression count, and two different figures circulate about LAIKA's films because they measure different things. McLean has described splitting a puppet's face into an independent upper section (the brow) and lower section (the mouth) that print and swap separately, so a comparatively small library of printed pieces recombines into a far larger number of performable expressions -- the source of headline figures like Kubo's reported 22 million possible facial expressions, more than fourteen times the roughly 1.5 million the studio's older system supported. On Kubo, LAIKA also printed its first fully 3D-printed character outright, the Moonbeast (voiced by Ralph Fiennes): 850 individual exterior pieces built around 250 separately printed internal armature parts, rather than a hand-fabricated puppet fitted only with printed replacement faces.
The Academy of Motion Picture Arts and Sciences recognised the technique with a Scientific and Engineering Award (Academy Plaque) to McLean and former LAIKA facial-animation designer Martin Meunier at its Scientific and Technical Awards presentation in February 2016 -- among the first such Oscars given for a stop-motion fabrication process rather than a camera or optical system. The workflow it recognised kept evolving afterward: Stratasys's case study describes a shoot-responsive pipeline in which an animator can "animate a unique line of dialogue, specifically for that one shot in the movie" and have the matching face designed, printed, cleaned and delivered to set for that single shot, rather than pulling only from a pre-built inventory prepared months before production began.
Workflow
- An animator or facial-rigging artist designs the required expression as a digital sculpt, typically split into an independent upper (brow) section and lower (mouth) section so each half can recombine with other printed pieces.
- The sculpt is sent to a full-colour, multi-material 3D printer -- LAIKA has used an Objet Connex3 and, since Kubo and the Two Strings, a Stratasys J750 with Voxel Print -- to produce a single physical part in the puppet's exact skin colour and texture.
- The printed piece is cleaned and any support material removed before it is fit-checked against the puppet's face rig.
- The finished part is catalogued into the puppet's replacement library alongside the other printed faces built for the production.
- On set, the animator selects the physical piece matching the shot's required expression and swaps it onto the puppet between exposures, exactly as with any other replacement-face system (see replacement-face-systems).
- For a dialogue line unique to a single shot, the same pipeline can run on demand: design, print, clean and deliver a bespoke face directly to set rather than drawing only from the pre-built library.