If you were interested in proto-electronic experimental music in the 1960s, one of the best labels to collect was the French Prospective 21e Siècle.
I'm fortunate enough to have a complete digital archive of remastered vinyl rips from the collection. They are not available commercially but a dedicated producer and DJ in England did a magnificent job with them. I was also incredibly lucky to find four of the original LPs in my travels. Three of the four are pictured below.
They are instantly recognizable by their stunning metallic foil covers. The designer is unknown and forever lost, but these wonderful recordings remain.
Thanks for looking!
Those look really cool.
I love the diversity of sound committed to vinyl!