flexible endpaper
An endpaper designed to provide a flyleaf that is
heavier than a single sheet of paper, but is still
flexible enough to not interfere with the opening
of the book. Developed at the workshop of British
binders Roger Powell and Peter Waters between 1960
and 1965, this endpaper is constructed by tipping
two folios together in two places: along the spine
and along the fore edge.