Quick lesson in 3D printing....
Imagine a cake decorator (bag of frosting with little tiny plastic/metal tip)
Use the cake decorator moving back and forth to lay a layer of frosting in the table
Let it cool a bit
Add a new layer on top
repeat this until you have a cube of frosting
You just 3D printed a "cube"
Now make it a machine not you
Now make it plastic instead of frosting
Now make the hole at the end of the "decorator" 1/10 of a millimeter across
That is for plastic printing
Metal is done the same way but it is ultra fine metal powder mixed with a bonding agent(epoxy)
after making it they sinter (HIGH temp bake) it to remove the moisture and fuse it back into solid(ish) material
Fine metals like Silver are done with the printer printing the "wax master" and then using traditional lost wax casting make the silver part.