Metallic microchannels with a three-dimensional (31)) configuration were fabricated by the spacer method. When spacing aluminum wires were shaped into a 3D-spiral configuration in an initial powder compact, they were easily replicated after the sintering and dissolution, resulting in 3D-spiral microchannels in a bulky copper body. This suggests that the spacer method is an effective way of fabricating complex 3D configuration microchannels, compared to conventional fabrication methods, for example, aligning and stacking two-dimensional microchannel layers. The compaction conditions for initial powder compacts, such as compaction pressure, spacing materials and compaction mode (uniaxial or isostatic), severely influence the shape and surface roughness of the resulting microchannels. (c) 2007 Elsevier B.V. All rights reserved.