was to make Grievous "iconic" and "scary". Numerous illustrations were developed at Lucasfilm, some purely mechanical and others more alien-like in appearance. One drawing presented Grievous as an eight-year-old alien child on a hover chair guarded by two IG assassin droids, which Lucas rejected for not being threatening enough. Another rejected robotic design was ultimately used for Grievous' IG-100 MagnaGuards in the movie. Two weeks after Lucas' instruction to design Grievous, a sketch made by concept artist Warren Fu was chosen and developed by Lucas for the character's finalized appearance. Fu took inspiration from the top view of a spray bottle for the design of Grievous' face. Fu's sketch was made into a -tall maquette sculpture which was then refined into a realistic computer-generated model by Industrial Light & Magic (ILM). This was one of the most complex models ever created by ILM at the time as many of its components were of differing physical qualities. Comparisons have been drawn between Grievous' appearance and Jacob Epstein's sculpture Rock Drill. In the lead-up to Revenge of the Sith, Grievous made his first ever appearance in the season two finale of Clone Wars. The character's voice was provided by John DiMaggio. Grievous would return in a more prominent capacity in the third and final season, with Richard McGonagle replacing DiMaggio in the role. Numerous actors auditioned for the role of Grievous in Revenge of the Sith. Lucas wanted Grievous to sound as if he was speaking through a cybernetic voice box, so every audition was put through the same computerized layer of processing by Matthew Wood, supervising sound editor at Skywalker Sound, to create a "synthesized timbre". Gary Oldman, a friend of producer Rick McCallum, was initially cast in the role and even completed some voice-over work. Oldman had to drop out of the production due to complications that arose from the rules of union filmmaking in Australia where the film was shot. Having previously performed voices for other Star Wars projects, Wood took Lucas' feedback on the various auditions he modulated and submitted his own under the pseudonym Alan Smithee. Wood approached Grievous as a "classic villain" and used a gruff and harsh voice with an Eastern European accent for his performance. A "gravelly quality" was added to Wood's voice when it was processed. Lucas selected Wood for the role and, since he had bronchitis at the time, instructed Wood to