[entropy12]

First of all the material is concrete, not cement.
And concrete requires many hours to solidify and harden.
If the machine pushes out viscous material, it will change in
shape by gravity. All concrete pouring requires molds for this
very reason.

3-D printers are a joke. Good for making chocolate figurines and some small solid plastic shapes. For anything industrial strength components, the cost of building such machines will far outweigh conventional manufacturing.

[2ndDivisionVet]

Hit the keyword “3Dprinting” or “3Dprinter” here and prepare to be amazed.

[9YearLurker]

The world is changing on you—even though all applications are not yet mature.

[Jonty30]

If a project the size of Hoover Dam can be built in stages using concrete, there’s no reason why a house cannot be built using the same method and have a machine build it. It may take them 20 years to perfect the method, but there really isn’t anything special about concrete that, once everything is set up, why a machine cannot go about laying concrete in a systematic method, to ensure optimal results, cannot build it.

[CrazyIvan]

They are not a joke, bit a good deal of the hype about them reminds me of the flying car promises of the 50s. I have used one to make prototype parts to test for fit and appearance and it was very helpful. As far as making a usable product they are limited at this time.

[null and void]

3-D printers are a joke. Good for making chocolate figurines and some small solid plastic shapes.

And production rocket engines for the seven passenger man-rated Dragon V2.