The resultant volume -- which ultimately took at least one hundred years to finish, and included the entire Old Testament -- is known as the Septuagint (from the Latin word for seventy, for the seventy or so scholars who are said to have launched the work; the book is also known as "LXX," the Roman numeral for seventy).It is an anachronism to refer to the Septuagint as a "volume." At the time of its translation, and for centuries to come, the individual books were written out separately (first in scrolls and later in codices), and so all the scriptures together would take up at least a number of shelves in a library. (The earliest surviving complete Bibles in a single bound volume come from the fourth century C.E. and tended to contain more books than are in anyone's biblical canon today.*)
The fact that the books were originally not bound together is important because it made the concept of "canon" more fluid: whether a book belongs in a library is a somewhat different question than whether in belongs bound with other books in a single volume. I suspect that the process of translation took more than a century and, in any case, many of the books were subjected to repeated translation revisions, so there wasn't a single, authoritative Greek translation circulating for each book. This variety is reflected in the New Testament quotations of the Septuagint.
*Codex Sinaiticus and Codex Alexandrinus contained texts now included among the Apostolic Fathers. Codex Vaticanus is damaged but may also have included material from the Apostolic Fathers. The inclusion of these books in the volume doesn't necessarily mean they were canonical; they may have just been considered useful or edifying.
