Third-Eye Spellbook (3.5e Equipment)
From D&D Wiki
Third-Eye Spellbook: This spellbook is actually a small square gem that affixes to the owners forehead (occupying the item slot reserved for the head, similar to a phylactery). When activated by the appropriate thought, this gem projects an image of a spellbook in front of the owner. Turning pages is accomplished by willing the page to turn. This spellbook holds up to 50 levels of spells.
Scribing a spell into a third-eye spellbook requires that the owner meditate with the book open before them for a 24 hour period without interruption. The amount of time required to scribe the spell is not level-dependent. As they meditate, the spell is slowly scribed into the book in a language known to the caster. Spells can be erased from the spellbook by meditating with the book open to that spell and concentrating on erasing it over a four hour period.
When a third-eye spellbook is found it typically looks like nothing more than another gem in the haul of treasure taken from some poor unfortunate monster. A found third-eye spellbook only takes an hour to attune to a new owner. Spells in the book vary depending on the previous owner and require the usual amount of time and effort to learn any unfamiliar spells contained therein.
Faint illusion;CL 3; Craft Wondrous Item, Scribe Scroll, silent image; Market Price: 1,000 gp