hand made <#booklet=booklets> produced by Minnesota Diversified Industries. Most contained 15 <#wag=water-activated gum> <#sheetstamp=sheet stamps> placed within blue cardboard covers having a rectangular opening through which the stamps could be seen. By comparison, other MDI booklets contained <#selfadh=self-adhesive stamps> that were produced from pieces of <#web> originally intended to be processed into <#convbooklet=convertible booklets>. With these booklets, special die cut mats were used to create booklet panes of 14, 15, or 16 stamps that were glued into the blue covers.