Protective envelope for a book, magazine or exercise book, especially for school books, is made from a parallelogram or rhombus shape blank of elastic material that is folded over so that its edges can be sown together

摘要

Protective envelope is made from elastic material with at least four joining seams, whereby the material blank is cut in a parallelogram or rhombus shape. The four corners of the blank are folded into the middle to form a square or oblong shape. The cut edge sections of the four blank edges (1-4) are sown together and the inner surface of the square or oblong envelope has a central section that is parallel to the two side edges.