him to cast for the role. Nattawut noted that Thaneth's performance led him to modify the script and make the father less controlling, resulting in a more profound father-daughter relationship. The cast underwent acting workshops for a couple of months before filming commenced. Romchat Tanalappipat served as acting coach, and worked with the actors before and during filming. Special preparations by the actors include Chutimon practising writing with her left hand, as her character is left-handed, and Chanon memorising the value of pi to beyond the 30th digit. Filming Most of the filming took place in Thailand, while approximately 30 percent, by Nattawut's estimate, was shot on location in Sydney, Australia. Some ten crew members flew to Australia from Thailand, while most of the Sydney filming unit was sourced locally. Filming in Sydney was subject to many more restrictions than in Thailand, including strictly limited shooting times. A particularly challenging scene to film was a chase sequence shot at the underground section of Redfern railway station, which had to be fitted into the trains' normal running schedule. Nattawut had, since his early advertising work, frequently collaborated with cinematographer Phaklao Jiraungkoonkun. According to Phaklao, while most of Bad Genius shots were designed in advance, some were improvised and designed on set. Others, like the mid-story exam sequence, necessitated advance detailed storyboarding and blocking. Nattawut also noted the challenge posed by the exam scenes, as the mundane action forced him to rely on the camerawork to convey suspense; the mid-story scene in particular comprised 200 shots for four pages of screenplay. Compared to his earlier work on Countdown, Nattawut says he learned to accept more input from the cast and crew instead of strictly trying to fulfil his visions. He found that asking Phaklao for opinions on shots led to better results, and editor Chonlasit Upanigkit also helped with his keen sense during post-production. Stylistically, Nattawut says he was inspired partly by 1970s thrillers such as The Conversation, The Parallax View and All the President's Men, leading him to mix in a certain retro/vintage style in Bad Genius. Stills from The Godfather were used as a colour palette reference during post-production work with Kantana Post Production. Nattawut also used 2011's Tinker Tailor Soldier Spy as a reference. The retro style was also factored in the costume design, according to costume designer Pawaret Wongaram, who was also familiar with Nattawut from their work