Ive seen this before, however to say they 3d printed a glock is an exageration, as the 3d printed part is only considered a gun in us parlance.

Basically they printed a lower receiver which on the glock doesnt do alot other than contain the trigger mechanism and a recoil spring.

There are much more impressive 3d printed firearms where they have used it either entirely from 3d printing or designed presure containing parts that are designed for the qualities of 3d printed materiials