A celebrated snob remarked, writing about Christmas: 'The bigger the card, the lower the class.' One might well say the same about architects' portfolios. Year-out students are allowed to struggle in with an A0 portfolio catching the breeze, but for more senior staff an A5 Gucci leather photo pouch is the maximum acceptable bulk. The former is the equivalent of the gold embossed A4 hunting scene you receive from contractors, while the latter is the limited edition collectable from private clients with taste.
Those in a less elevated position will have to spend more time worrying about the content of the portfolio than its wrapping. The basic element has traditionally been a collection of one's best drawings. Equally traditionally, it also contains a selection of drawings by other people in the office with the initials in the title block Tippexed out.
Restricting your portfolio to your own work immediately puts you at every (except a moral) disadvantage when applying for jobs. Whether you display exquisite freehand hogback ridge details or computer renderings indistinguishable from photographs, a set of drawings that are exclusively your own suggests that you are a) drawing fodder, b) not commercially astute, or c) very pleased with yourself. Only one of these characteristics is valued in any office.
Brazenly showing a portfolio consisting solely of sheaves of textbook detailing by (supposedly) your minions and professional photographs of completed projects might be worth a try. If you can disguise your bemusement when asked about a project (ie if you don't say 'It was in Droitwich, I can't remember much about that') you are halfway to the job offer.