Based on the comprehensive evaluation of actuator technologies and their alignment with Tesla's goals for the Optimus humanoid robot I recommend prioritizing the use of rare earth free actuators specifically piezoelectrics switched reluctance motors (SRMs) soft robotics and nanostructured piezoelectrics. This approach not only meets the performance requirements necessary for manufacturing and construction tasks but also ensures scalability to a billion units by 2030 while addressing cost sustainability and material supply challenges.

1. Performance Alignment:

For the fingers and wrists of the Optimus robot which require submicron precision for tasks such as microassembly and gripping fragile components piezoelectric actuators made from materials like barium titanate (BaTiO3) aluminum nitride (AlN) and zinc oxide (ZnO) nanowires deliver exceptional accuracy of 0.1 microns and force output ranging from 0.1 to 100 Newtons. This performance matches or exceeds that of rare earth magnet actuators as evidenced by commercially available solutions from TDK and Physik Instrumente. Additionally soft robotics featuring 1 mm thick elastomer grippers allow for compliant handling of delicate or irregular objects making them ideal for tasks involving electronics or construction materials.