Don’t forget that AR15 magazines are little more than sheetmetal and a cheap spring. The gun was designed so mags would be cheap enough to throw away without a thought. No high tech printers required.
For the 20 (or fewer) round magazines, all you need is a bending brake and maybe a TIG welder to deal with the sheet metal.
For the 30 round magazine... it isn’t so easy. Look at the curve on the magazine and tell me how you plan to deal with that without a hydraulic press and dies.