The next prototype will feature an improved binding technique, including sanding the spine edges and adding a mull for enhanced strength. It will use lay-flat perfect binding, with a new cover and endpapers materials.
Two new materials that will be used in Prototype 2 are:

Gmund Heather (300gsm)
In appearance it’s like working with the very finest quality leather – sturdy and expressive

Takeo Tant Select TS-1 (116gsm)
Characterised by a unique double-sided embossing and a gentle translucence.