Here’s your corrected and polished version with minimal edits for clarity and correctness:
In the mid-’70s, I became San Francisco’s first professional male hand model. That’s a whole other story in itself. For three or four years, I was the only one in the field, and I built a nice (and profitable) reputation, shooting hand shots for all manner of products and companies.
Around April 1984, I got a call from one of my favorite photographers, Dennis Gray. He booked me for an hour and asked me to bring a variety of shirt colors, a couple of sport jackets, and a suit jacket.
I showed up, and a pale blue shirt was chosen. We began the shoot—I was simply to hold this weird little plastic thing in a variety of ways. After about 45 minutes, Dennis thought we had the shot. I then asked him, "What is this thing?" Dennis replied, "Darned if I know—they call it a ‘mouse.’"
A year later, I bought my first Mac, a 512. Unpacking it, I saw that virtually every surface of the box, plus all the manuals, had this hand on it. Oddly, I didn’t remember the shot among the many I’d done in the meantime. It only dawned on me a few days later that it was my hand!
The connection also brought me a variety of hand shots for MacWorld magazine (the December 1984 cover is pictured), and I was later told that my hand was the only "live" thing on MacWorld covers for its first five years of publication.
So, though I didn’t have anything to do with the creation of the Mac, I did contribute to its great marketing effort.
The mouse shot, by the way, paid me only $100. I don’t suppose Steve would be willing to pay residuals at this late date?
(Changes: punctuation, hyphenation, minor word choices, and corrected "it's" to "its" where needed. Kept your voice and tone intact.)