I'm very curious, where are new amendments to the original Constitution added? Are they kept separate, are they kept together? Do we unseal the original Constitution and add to it?
They are separate documents. There is no space on the constitution on which you could add the documents. Moreover the originals are kept in the sealed conditions in the National Archives. You can see the text of the original manuscript of the constitution and the amendments on there on display in the rotunda. Moreover, some amendments involve removal of text, not just addition, so even if you were to try to physically alter the text it would require destruction of the original document.
That being said of course, "the constitution" as it actually exists as a piece of law is of course actually amended by these texts, so a pocket copy of the constitution will have the 3/5ths compromise struck from the text, usually with a note referencing the 13th amendment.
