This section is from the book "School Needlework. A Course of Study in Sewing designed for use in Schools", by Olive C. Hapgood. Also available from Amazon: School Needlework: A Course Of Study In Sewing Designed For Use In Schools.
The four-holed metal button is manufactured from collets or disks cut from sheet metal. The under collet of the button is cut from tin, the upper collet from brass. Then the collets are shaped and the four holes punched by a machine. A piece of straw-board of the same form is prepared, and the three pieces are bound together by solidly lapping the edge of the brass or larger collet over the other two.