If you want a traditional ”fine- art” presentation of prints in a box, it is OK, but a book may be better. Even when it’s meant for gallerists, it is important to control the order in which they see your images—impossible with loose prints. A box is also a huge pain at a big in-person portfolio review, when you meet with many people back to back. With a box, the rule still applies: Put your name on it.
Portfolios usually need protection against dings or bent corners. A slipcase or bag with handles will suffice. It can be pretty and, again, doesn’t have to be black. But don’t put the book in a slipcase and the slipcase in a bag. Oh, and have I mentioned this yet? The bag. Your name goes on it, too.