MDI booklet

MDI booklets, nicknamed blue booklets, are US postage stamp booklets made by Minnesota Diversified Industries beginning in the mid-1990s.

The standard design, different from USPS booklets, was a dark blue cover with a window showing the stamps within. There are varieties of booklet covers. Stamps used included both gummed ("water-activated") and self-adhesive definitives as well as commemoratives. These were handmade from blocks of sheet stamps, folded in all kinds of ways. Booklets of 15 had a stamp removed from a block to correct the count.

They were used for standard USPS vending machines as well as improvised standard vending machines.

Study continues on varieties of booklets that were made.  File:US MDI booklet A.jpg|32c self-adhesive angel Christmas stamp booklet of 30. Note closure by self-adhesive sticker; some booklets are known cellophane wrapped. 