A method and apparatus for embedding features and controlling material composition in a three-dimensional structure (130) is disclosed. The invention enables the control of material characteristics, within a structure (130) made from a plurality of materials, directly from computer renderings of 
solid models of the components. The method uses 
stereolithography and 
solid model 
computer file formats to control a multi-axis head (480) in a directed material 
deposition process (123). Material feedstock (126, 127) is deposited onto a pre-heated substrate (19). Depositions (15) in a layer-by-layer pattern, defined by 
solid models (141, 146), create a three-dimensional article having complex geometric details. Thermal management of finished solid articles (250-302), not available through conventional 
processing techniques, is enabled by embedded voids (152) and / or composite materials (126, 127), which include dissimilar metals (210, 216). Finished articles control pressure drop and produce uniform 
coolant flow and pressure characteristics. High-efficiency 
heat transfer is engineered within a 
solid structure by incorporating other solid materials with diverse indexes. Embedding multi-material structures (132, 134) within a normally 
solid component (141) produces articles with diverse mechanical properties. 
Laser and 
powder delivery systems (420, 170) are integrated in a multi-axis deposition head (480) having a focused 
particle beam (502) to reduce material waste.