A process (and apparatus for performing the process) for layer manufacturing a three-dimensional work piece comprising the steps of: feeding raw material in a solid state to a first predetermined location; exposing the raw material to an electron beam to liquefy the raw material; depositing the raw material onto a substrate as a molten pool deposit, the deposit having a forward edge region in an x-y plane with a forward edge region width and a trailing edge region in the x-y plane with a trailing edge region width, under at least one first processing condition; monitoring the molten pool deposit for at least one preselected condition using detecting of scatter from a scanning electron beam contemporaneously with the depositing step; solidifying the molten pool deposit; automatically altering the first processing condition to a different processing condition based upon information obtained from the comparing step; and repeating steps at one or more second locations for building up layer by layer, generally along a z-axis that is orthogonal to the x-y plane, a three-dimensional work piece.