Yes, 12-strings were indeed hard ( = nearly impossible) to come by in the 1950s. As I recall it, no major guitar maker made them. My first c. 1957 was a giant made I think by a Portuguese-American from New Bedford, the neck too long for contemporary strings, which were shorter. The next c. 1958 was a smaller Mexican model that sounded beautiful but snapped its neck, the wood like cheese. (The famous cactus-wood guitar?)

When Martin finally started making them I couldn't afford one. When a friend and fellow singer acquired a cutaway Martin 12, I was plagued with thoughts of burglary.

Thank goodness for Alvarez.

Then, of course, Jim/Roger McGuinn & the Byrds made it a standard-line instrument c 1965. Even Pete Seeger hadn't been able to do that.

Bob