Creating a character that looks like a doll but emotes like a human is notoriously difficult. The team behind the (primarily a small German studio) utilized a technique known as "puppet-based rigging" integrated with particle physics.
: Analysis often centers on how Sally chooses to use her physical appearance rather than her intelligence to escape her home life. (Isaac Asimov Short Story) sally animated short
This 1980s Czech animated short gained legendary status as "lost media" before being rediscovered. It originally aired on Nickelodeon’s Key Themes Creating a character that looks like a doll