a) a housing having at least one interior frame defining a chamber within said housing for producing three-dimensional objects from a building medium;

b) a container for the building medium adapted to be received within said chamber and releasably fixed in position with respect to said frame;

c) a source of energy within said chamber for supplying energy to selected portions of a surface layer thickness of the building medium in said container to solidify the layer portions;

d) a build platform for supporting solidified layer portions of building medium, said build platform adapted to fit within said container beneath the surface of the building medium;

e) an elevator translatably fixed to said frame for vertically upward and downward movement and extending horizontally into said chamber to releasably secure said platform on said horizontal extension, thereby to raise and lower said building platform;

f) a cart releasably fixed in position with respect to said container of building media and having telescoping arms for receiving said build platform and three-dimensional object and removing these from said elevator; and

g) a controller operatively connected to said energy source, said elevator, and said cart for controlling supplying energy to the building medium, for vertical translation of said build platform, and for removing said build platform and the three-dimensional object from said elevator.