Please allow me to introduce myself briefly here, too.
Though my primary occupation at present is teaching English-as-an-additional-language (EAL) to speakers of other languages in Japan, and my only current explorations through portfolios are for EAL students in intermediate-level writing courses, my attention first turned to portfolios long ago, in a land far away, when and where I assembled selected drawings, paintings, and photographs for critiques in a sturdy cardboard folder too large to transport easily by bicycle. Twenty-five-odd years or so later, I digitized the remnants.
Representations of plastic arts, in the day, consisted largely of 35mm color slides. Computers filled rooms, and input methods depended mainly upon key-punched computer cards. Other artifacts included z-fold printouts from dot-matrix printers, hardly conducive to peer review by any but hard-core programmers. The print-outs often filled arguably accessible and portable ring-binders, as could most artefacts of learning and teaching materials not stored in less accessible and less portable boxes, bins, or filing cabinets.