It’s a good candidate since it sounds like there’s no precision mechanical components like there would be in a hard drive. Does anyone have ideas for how I’d go about this? Is there a barrier I’m not considering?
I know how to make basic semiconductors already, so that’s not an issue.
Edit: I’ve got an answer written down in the comments now. TL;DR you’d still need lithography to do it the OG way, because of the patterned magnetic material that directed bubbles around the medium, but material requirements are actually pretty flexible.
Sam Zeloof has made chips in his garage and posted a whole series about it on Youtube. He bought his silicon wafers, he didn’t grow them, and his machines do take up the whole garage - but he did the whole thing himself. Fascinating viewing IMO. I don’t know anything about where one would get these garnetty materials you mention, though.
So, I’m still doing research, but it seems like any ferrimagnetic thin film should work.
Rare earths would have been in lower demand at the time I think, some garnets have useful magnetic properties, and growing garnets is relatively easy. Similar synthetic crystals are common as lasing mediums now.