Transmute Spellbook

Transmute your spellbook into a small common item of your choice that is no larger than your hand for easy carriage.  This works for ordinary spellbooks or spellbooks with special properties.  If the spellbook in its new form is reduced to 0 hp the spell ends and the spellbook is transformed back into its original shape undamaged.  It starts with 5 hp regardless of the shape and needs to be the target of an attack to be damaged.  The new shape is not damaged by fire or water or other elements without a specific attack being made targeting it regardless of the apparent shape.  The spellbook transforms instantly back to its original shape or into the same transmuted form as many times as desired with a verbal command until the spell ends or is terminated voluntarily, at which point it takes its original form.  Spells cannot be learned from or transcribed into the spellbook in its transmuted form, but it does count as being carried for effects dependent on that.  

The spell can only be used by a single caster on a single spell book.  If the spell is applied to a new spell book, any previous spell books transmuted return immediately to their original form at the feet of the caster or closest equivalent.

If the spell is cast every day for a year, then it remains in place permanently unless the spell is terminated deliberately.  Each time the spell is cast a new form can be chosen, but for each casting the same form must be used when the spellbook is transmuted.