An apparatus for preparing a two-dimensional layer of a three-dimensional object during three-dimensional printing of the object. The apparatus may include a controller; a transparent substrate for receiving a deposited layer of liquid materials on an upper surface thereof; a selective deposition unit that deposits at least one liquid body material and a liquid support material different from the at least one liquid body material, on the transparent substrate according to signals received from the controller; and a selective curing unit that selectively solidifies, by curing irradiation, a portion of the deposited layer of liquid body materials on the transparent substrate according to signals received from the controller, such that some of the liquid body material remains uncured.