ELI5 3D Printing - Does NASA really email tools to space?

How does NASA effectively email physical tools and equipment to astronauts on the Space Station? If you 3D print a vinyl record from an MP3 file, is the music digital or analog? How exactly does 3D printing work like a computer-controlled hot glue gun? Why is 3D printing a game-changer for prosthetic limbs? Why can't 3D printers replace traditional factory assembly lines for mass-producing everyday items? ... we explain like I'm five Thank you to the r/explainlikeimfive community and in particular the following users whose questions and comments formed the basis of this discussion: genelatifah, fyre2387, flamedieout, dkf295, mroctantis, atrain82187, t0m0hawk and nola-kola To the ELI5 community that has supported us so far, thanks for all your feedback and comments. Send us an e-mail: [email protected]