What is this obsession of his with buttons? He mentions buttons in at least four of his confirmed letters. And the "button" letter itself, the Johns letter and the "little list" letter all begin with him harping on about the people in the SF area not wearing Zodiac buttons.
That he was an attention seeker and wanted his fifteen minutes is obvious – but why this particular obsession? Did he see buttons as the ultimate form of recognition? You weren’t truly famous until you got your face (or symbol, in his case) on a button? He had a huge movie production made in his "honor" (DIrty Harry), which he doesn’t comment on at all – but the fact that people aren’t walking around with Z buttons…now that vexes him to no end and he can’t stop moaning about it.
IDK…..maybe he was a little ocd and liked the fact there were two "t’s" or he was fascinated by logos as working for a company such as a major car co. (eg. Lincoln Mercury Division Ford Motor Co., Mercedes/Benz et al) gave him great awareness of brands and he liked the hood ornaments on cars. He knew he’d never get his picture on a dollar bill or one of higher denomination or be remembered by a coin or a stamp so thought a button would be good since they were very common (election campaigns, peace symbol, etc.) He knew he’d never be remembered as a great composer from having taken classical piano, perhaps. He wanted to be remembered as actors and artists are known for their body of work imo!
He may have had cars on his mind and knew he’d never be known for inventing one and jokingly told someone people could be referred to as Model 2014’s (for example) if they were born this year just as cars are distinguished by the year they are presented.