After all the crazy stories about being on set for Batman v Superman: Dawn of Justice, Michael Shannon was actually never in the movie! Jesse Eisenberg explained on Conan that they created a General Zod dummy for him to act with. studioADI is the company that created the dummy, and they just released a video showing how it came to life.
For the blockbuster Batman v Superman: Dawn of Justice, ADI created two ultra-realistic replicas of the deceased General Zod that would withstand close scrutiny by a camera lense. Fitness trainer Greg Plitt came to ADI for us to lifecast his body from the neck down while our colleague Barney Burman loaned us a headcast of actor Michael Shannon. Once the Shannon headcast was copied both the head and body were run in silicone with a polyfoam fill to make them solid. Tony Matijevich, Brian Clawson, and Tim Leach created both Zod bodies; Denise Baer punched hair; Mike Larrabee painted both Zods.
Unfortunately Greg Plitt died before the movie was released. studioADI has dedicated the video above in his memory.