Stuart Freeborn was the head designer of the Yoda team, and Wendy Froud (wife of Brian Fround -- a famous dollmaker who worked on The Dark Crystal) was the main fabricator. Oz and Gary Kurtz were also part of the Yoda team. Henson really didn't do anything except let the aforementioned parties tap the talents of his staff (most of whom were working on The Dark Crystal at the time, so Yoda was a test-run for their attempts at using realistic puppets to tell a fantasy story).