On September 17, 1787, the final draft of the Constitution of the United States, written to replace the Articles of Confederation, was signed by 39 of the 42 delegates still at the Constitutional Convention in Philadelphia.
Shown below (and accessible here) is a printed copy of the Constitution with marginal notes by George Washington from September 12, 1787.
You can also view pages of the diary that Washington kept at the time, here.
What about the delegates who didn’t sign? One of them was George Mason of Virginia, who objected to the omission of a Bill of Rights. (These were finally adopted on December 15, 1791.) Elbridge Gerry of Massachusetts (of gerrymandering fame) had a number of objections you can read about here. The third was Edmund J. Randolph of Virginia, who was worried about states’ rights. Later on, however, he changed his mind.
On the excellent Library of Congress (LOC) website, you can access Eliot’s Debates, a five-volume collection compiled by Jonathan Elliot in the mid-nineteenth century which, according to the LOC, remains the best source for materials about the national government’s transitional period between the closing of the Constitutional Convention in September 1787 and the opening of the First Federal Congress in March 1789.