I think Martin also made some with HPL (Formica) tops and it was those I was thinking of.

Back and sides aren’t so important in sound production - although in mandolins a carved back adds a surprising amount to the overall sound.

The main problem with such materials is their repairability. A luthier friend of mine carefully spliced back together a 60s Martin which another friend fell on when he stupidly decided to ski to the local session with it on his back in a gig bag one snowy night. I doubt he would have ben able to get an HPL guitar repaired.

I shudder to think what different sort of hide glue Gibson was using between 1958 and 1960!!!!