Espresso Drinks coffee Forever Postage Stamps

Cups of four different coffee drinks, drawn as digital illustrations: the espresso family broken down into its recognizable members, each shown from above or in cross-section so the proportions of coffee to milk are actually legible. It is a more informative stamp than it looks - the difference between the drinks is exactly those proportions, and the illustrations show them rather than naming them.

Coffee businesses are the obvious buyer: roasters, cafes and subscription services use them on invoices, thank-you cards and packaging inserts, where a flag would be a wasted opportunity. Beyond that they carry invitations, thank-you notes and general correspondence perfectly well. Booklets of 20, self-adhesive, four designs repeating through the book so a run of envelopes does not all carry the same cup. Forever value, so each stamp covers a one-ounce letter at the current rate no matter what the book cost when it was printed.