My former neighbor Thelma got a set of Ekco Flint cookware when she and her husband Nelson married in 1954. She used it until she passed away about 10 years ago. It still looked like new.
The best description of National Homes is "panelized". The components were produced in a factory, and assembled at the job site. There is a development a couple blocks from me that is National, and were built in the mid 50's.