The Cooper Union library has a small trove of primary sources related to the school’s history in its archives. To access most you need to make an appointment first by writing email@example.com.
BUT, some of the biggies—the Charter, Bylaws, Deed of Trust, and Peter Cooper’s letters to Trustees—are digitized and live here on their site:
If you prefer viewing a digital copy of a print copy (like I do), check out the free Google Book version:
Charter, Trust Deed, and By-laws