Long before DVDs, CDs and diskettes in magazines were a thing we had playable records as attachments. They were not real vinyl, I guess, but out of flexible plastic. The ones I remember were about the size of a single but square and also just one-sided.
I had one, in a "Bloom County" cartoon book[1]. It was a flexible black record the thickness of a thick sheet of paper. It even had a spot to place a coin because the black plastic was thin and slippery. It played pretty well though and had two sides.
Someone is selling one on amazon with a decent image.
edit: see the comment with the art article about "Flexi-disc"
As an interesting aside in the "alternative record formats", when as a child I had the "mickey ghost chasers" book. It came with a little hand held box, which you'd put over mini "records" imbeded in the books[2]. You 'd hit a button and it would play audio. The underside was like a weird mini-upsidedown record player
Apart from flexi discs, the strangest example of a record I came across was Action Man figures in the late 60s and early 70s. They were a UK licence of GI Joe.
The 1962 Seattle World's Fair had postcards that were playable on record players. Some of them are still sold today, I was gifted one a few years back.
My favourite method for distributing software was hapening during 80s on Czechoslovak television, there was some tech/computer show and at the end, during credits they play sound that when you record it (and was lucky) you’ve got some small game or something.
