mechanics joints - Google Search
Soldier , Stefan Celic on ArtStation at https://www.artstation.com/artwork/E4xYe
LIMBS International, a non-profit that is committed to restoring mobility to millions of amputees around the world, has designed a highly-functional, innovative, ultra low-cost, prosthetic knee.
ArtStation - Bionic foot, Hristian Ivanov Shyne
3D character model for Soldiers Inc: Mobile Warfare Created by 3D Art Team Lead Vladimir Silkin https://www.artstation.com/artist/heat3d © Plarium, 2016
Ausarius, Yutthaphong Kaewsuk on ArtStation at https://www.artstation.com/artwork/16XEq
Chappie desk figure.