A paper written in one's own handwriting

One word substitute is Manuscript.

Manuscript: a book, document, or piece of music written by hand rather than typed or printed.
Scroll: a roll of parchment or paper for writing on.
Parchment: a stiff, flat, thin material made from the prepared skin of an animal, usually a sheep or goat, and used as a durable writing surface in ancient and medieval times.
Transcript: a written or printed version of material originally presented in another medium.