The thing on magazines, is, that the magazine follower shape has to work in unison with the spring pressure and feed lips, and that is hard to get right on paper. Things like that are modeled, tested, and adjusted until they're correct. There might be several redesigns of the same magazine, before it is correct. Then, they measure the working model for the final design.
3D CAD modeling will not get those correct, since what looks to work in a computer may not in real life, as magazines designs can by unpredictable, until they are adjusted and tweaked to make them work. Once they get the measurements on a working magazine, then they make the dies to form the lips, body, and the follower, unless the latter is molded, etc. Even at this, I've seen new magazines that needed tweaked to work. It is all in getting it to guide or steer that cartridge straight into the chamber, while still securely holding the other rounds in the magazine.