Ease of exit was not a required feature of the ancient pyramids, and some 5,000 years later the situation hasn’t improved much. Grovelling on all fours to deal with the zipper at lower end of the hypotenuse is a pain in the neck, especially after re-entry. A two-way zipper offers a tempting and ergonomic solution, but squeezing out between the teeth is a likely path to zipper failure. So how about a different door altogether…luxury!






