By which I mean who physically wrote it/whose handwriting is on the original draft?
It would seem a simple question but I’m having trouble googling the answer and I’m away from my library at the moment. (I know that the wording of the final draft was by Governor Morris but I’m not sure if it’s his handwriting.)
The constitution wasn’t originally written, it was printed from notes by two printers named Dunlap and Claypoole. After being printed up, Washington ordered that the Constitituion be “engrossed”–rendered into large handwriting and signed as a legal formality. The only record concerning the engrossing is for $30 to be paid to the clerks, but it is believed that the engrossing was done by Jacob Shallus, the assistant clerk for the Pennsylvania State Assembly who was officed in the building where the convention was held.
http://www.uh.edu/engines/epi1003.htm