I'm not sure what you mean with "portfolio". There is a gallery of the photos you took and shared on rec.net , e.g. https://rec.net/user/gribbly/photos . These are relatively good quality, and you can download them.
Each room has also a gallery of the photos that were taken in that room. You can see those photos in-game on the room's details page.
There is also a "portfolio" of each player in-game, which includes rooms, inventions, and announcements by that player. Rooms have a cover photo, which is one of the photos that was taken in that room. Inventions have a cover photo. And announcements can also include a photo as far as I know.
As far as I know there is no good way of "saving" a photo in-game. The best I can think of is to print out the photo when you take it and save it to an invention. (But that's difficult when you are not allowed to make an invention in the room where you take the photo.) I haven't tried out making announcements with photos, which might be another way of "saving" them.
