Here's a fun ad from 1963 for Lee Swimsuits. It identifies the fabric as Creslan knit, a miracle of figure moulding. An interesting side tidbit when researching Creslan on Wikipedia, I found out it's an Acrylic fiber which has since ceased production in the US.
"All US producers have ended production. Former U.S. brands of acrylic were Acrilan (Monsanto), Creslan (American Cyanamid), and Orlon (DuPont). Other brand names that are still in use include Dralon (Dralon GmbH)."
Love the high waist two piece in white, about $12.00 in 1963 ($90.00 in today's dollar). I'm seeing lots of this type of high waist swimsuit being reproduced from today's manufacturers as well, but I prefer the original vintage garments. Something about the fabric, the shapes, the support, the figure enhancing fit and the definitive silhouettes of the periods just can't be matched today.