These three Japanese greeting cards date from the 1980s, and they are all the work of Masahiro Chatani. He was a Professor at the Tokyo Institute of Technology, and he is considered to be one of the founders if not the founder of a technique called Origamic Architecture.
The designs sometimes show architectural forms, or they can also demonstrate geometric patterns.
Initially he just gave his cards away to friends and family. But he went on to write over 50 books on the subject, and he felt that these designs helped people appreciate the complexity of three dimensional designs, and also inspire an interest in mathematics and art in young people.
Professor Masahiro Chatani died in 2008.