This double-sided 6-image extendo principle was invented
by me in April of 1998, while on a Structural Graphics payroll
to advertise Glen Allen wines. I called it "Sixtendo".
Later on this principle was used dozens of times by
Structural Graphics, and has been an inspiration
for numerous products of Burgopak (UK), holders of the
European extendo patent.
Click on image to see initial Glen Allen sixtendo.