Nathan Maynard-Ellis who is alleged to have killed Ms Rawson as the culmination of "years of pent-up fantasy" and desire, told a court he started making horror-themed masks after being asked to raise funds for charity at Halloween.
Maynard-Ellis, 30, and his boyfriend, 25-year-old David Leesley, both deny murdering Ms Rawson at their "flat of horrors" in May last year.
Coventry Crown Court has been told the victim's body was cut into 11 parts and dumped in undergrowth near the defendants' home in Mission Drive, Dudley Port, Tipton.
Maynard-Ellis, who had met Ms Rawson, 42, by chance in a pub in Dudley, also denies historical rape allegations made by a woman following his arrest.
Giving evidence in the third week of his trial, Maynard-Ellis, who has been diagnosed with depression and Asperger's syndrome, told jurors he was bullied at school but had gone on to achieve a distinction on a special effects, film, television and theatre course.
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Asked whether an interest in films and books found at his flat had made him want to "try to re-enact any of it in real life" or "take action" from a film, Maynard-Ellis told jurors: "No. I have looked at films to make costumes and masks and things - but not to act them out."
Maynard-Ellis, who was assisted by an intermediary sitting near the witness box, added that the content of the films had not made him want to behave in a "violent or sadistic" way.
Invited to tell the jury panel about the effect his mental health issues had had on him, he said: "I just lose a lot of time and can't stand being around enclosed large groups of people."
Maynard-Ellis said he "just wasn't happy" after being bullied at school, and claimed he had stopped taking his prescribed medication around a week before Ms Rawson's death.
Asked by defence QC David Mason if he was "pretty good" at making horror masks, Maynard-Ellis responded: "I left with a distinction from college and I continued to self-teach myself, to progress to higher grade materials and castings and things.
"It started with me doing charity events for Halloween. Somebody in my friend's family had had cancer and they were trying to raise funds for a cancer ward.
"I was asked originally to make costumes and do people's make-up and prosthetics."
Addressing the rape allegations levelled against him, Maynard-Ellis denied making even a threat to the complainant.
The trial has heard that Maynard-Ellis told a psychiatrist he struck Ms Rawson with a rolling pin after she made "moves" towards him. According to his account to the psychiatrist, Maynard-Ellis then took Ms Rawson into a bathroom where he tried to wash her injuries, but realised she had died.
Jurors have been told Maynard-Ellis's defence case is likely to raise the issue of diminished responsibility.
Opening the prosecution's case at the start of the trial, Crown counsel Karim Khalil QC claimed Maynard-Ellis had harboured dark thoughts for many years "focused mainly on the sexual assault of women and their violent killing".
Mr Khalil added: "He has shown a particular interest in certain themes involving serial killers and the dismemberment of bodies.
"His boyfriend, David Leesley, knew of these interests, since their flat was full of printed materials, DVDs and videos about serial killers and the violent sexual abuse of women."
The trial continues.