This was an amazing find. They are from the "昭和" "showa period" . The "showa" period is from 1926-1989 but these are at about 25-30 years old . This is called "型紙" or "katagami". This is a stencil that was used to make "kashigata" (for more information on "kashigata please see below).
This one is made from paper-but not flimsy normal paper....this is wonderful thick Japanese paper and it is in fabulous condition.
This stencil could be used but it would also be fabulous framed and hung on a wall.
There is a kanji (chinese writing character in Japan) "三" "san" = "three" and it is surrounded in "井桁" "igeta" = "rhombus". A family name is called "mitsui" 三井 = one of big and powerful family running many business like bank, investing company, airplane factory, real estate and etc.
The stencil measures about 12cm x 8.5cm