The versatility of the Grogu puppet was also due to the incredible level of detail that the artists over at Legacy Effects poured into him. Amusingly, the character’s pointed ears proved to be one of the most difficult challenges when it came time to ensure Grogu was camera-ready. They had to show just the right amount of red veins, and it took four attempts to achieve the translucent look the VFX artists were going for.
For Grogu to be convincing, he also had to deliver a wide array of emotions ranging from curiosity to fear. That meant Legacy’s rod-controlled puppet had to emote and act on command while avoiding the edict handed down from Jon Favreau to avoid too much cuteness and needless fan service. As a result, at any moment, there were three or four puppeteers (John Rosengrant included) trying every kind of combination with the mechanics in order to strike the right mixture of facial expressions and body movements. They all had to work in concert to sell the effect. Fortunately, judging by Pedro Pascal’s reaction at the end of season 2 when the Grogu puppet brought tears to his eyes, the people at Legacy have absolutely done their job.
Speaking of which, the prototype Grogu puppet was given a few minor tweaks and improvements to make it a little easier for the puppeteers to control him in “The Mandalorian” season 2. “We went inside and tuned him up, made sure all his servos were fresh and good,” said Rosengrant. “But it’s the same character, you wouldn’t know the difference.” Apparently, even Grogu needs a tune up every once in a while.
Source : https://www.slashfilm.com/1261536/operating-mandalorian-baby-yoda-puppet-more-complicated-than-it-looks/