Patent ID: 7725209

Claim:
A three-dimensional printing system to print a three-dimensional object, the system comprising: one or more printing heads; two or more replaceable cartridge apparatuses storing building materials in a closed container and connectable via tubes to the one or more printing heads, the cartridge apparatuses providing building materials to said one or more printing heads to print said three-dimensional object; two or more sensors that determine the status of building materials in said cartridge apparatuses; a controller that receives data from said sensors and controls switching of building material supply from one replaceable cartridge to another; and a valve matrix coupled to said two or more cartridge apparatuses, to control supply of building materials from said cartridge apparatuses to said printing heads, wherein upon lowering of the level of said building material in any one of said two or more cartridge apparatuses to a pre-determined amount, said valve matrix is adapted to automatically switch material sources.