Unknown (to me) carbine magazine

[dnikkor]

Couple of simple questions - 1) Could I modify, manufacture or copy the item with pieces and parts readily available? Anythings possible if you toss enough money at it, though I don't believe you could simply modify an existing 15-round mag to recreate this one.
2) Why is this showing up now, 65 years later? Judging from the wear and tear, it has been around and used by somebody since whenever it was made, be it 65-years or whatever. The owner before me didn't have a clue what it was (and apparently didn't care either). I did care and here we are.
3) what does this item do that other (real) items didn't do back in that era?

Nothing except not being accepted into mass production.