In 1980 Alberca et al. described a patient with a syndrome of increased muscle irritability, who presented ondulating muscle rolling movements and electrically silent cramps, myoedema and muscle reactions to mechanical stimulation similar to myotonic response, suggesting a disfunction at myofibrillar level.
For c-3po, it was a costume, Anthony Daniels played c-3po: For R2-D2, It was a costume and a remote controlled robot. CGI was also used in the prequel trilogy. So, they had Kenny Baker to play him : And from Portrayal section of wookieepedia article on R2-D2 :
Grease 2 (1982) was a sequel to Grease starring Maxwell Caulfield and Michelle Pfeiffer. As mentioned, only a few cast members from the original movie such as Dody Goodman, Sid Caesar, Eddie Deezen, Didi Conn, Dennis Stewart and Eve Arden reprise their respective roles.