I understand there's a whole movement to machines that can make arbitrary objects. Usually, they're step-motored plastic fabricators, that melt plastic into specific shapes, given to them by CAD design. They also have a second compound that melts away in water, so one can cast shapes that would have fallen apart without support, but can become their final shape after a quick rinse. (Like an arch. It would have collapsed without support while building, but once built, the supports can be taken away because now the keystone holds it in place.) Most of these can make a very large percentage of their own parts, thus being semi "self assembling."
Some examples of this include the reprap, the "cupcake", Fab@home, and even a "gadget printer".
I love it because it's the closest we can have with today's technology to the "replicators" of science fiction that can grind out anything of your choosing. And maybe 99% of all jobs would disappear if that sort of thing became common, but in the right milieu , so would the need for jobs. I especially like that they can make copies of themselves, as most of them are rather expensive. (The cheapest one costs $500 USD!) And yet the plastic parts they're made of cost maybe 50 cents total, and the metal nozzle on the extruder is maybe another $3 at most.