Envelope with tongue fastener is made by folding parts along dotted lines, then introducing tongue into slit

摘要

The envelope consists of a plane sheet of paper and is made by folding the parts (3,4) along dotted lines (5,6). The tongue (10) is then introduced into the slit (9). Initially this tongue is folded towards the edge (11). Secondly the tongue is folded into the space (12) between the slit and the edge. The second folding enables an efficient fastening with the tongue between the parts.