NOT A BUTTON, AND WEDGE

How often in the lectures or lessons on a stand, posters and other visual AIDS? Of course, stationery buttons! In recent years, however, they comes to the aid of sticky tape. However, neither one nor the other can not be called gentle fixtures — they spoil what keep. Universal and yet does not harm the posters device can be made of conventional rails. Connect the three strips of different width so that between them formed a groove — it will hold, for example, maps: it is enough to jam the cut sheet of rubber or conventional eraser wedges; and the — beveled fourth rail.