Complementary surface fabrication processes such as molding, casting, embossing, and so forth, are used to produce articles, structures, or components structured to operate as sandwich waveguides. Resulting complementary surface artifacts include, for example, optical quality surfaces on wall parts, other exposed artifacts that occur where a complementary solid surface contacts non-solid material during fabrication, and sub-surface artifacts such as integrally formed connections between wall parts and base parts. A body whose surface includes a waveguide's inward surfaces, outward surfaces, and light interface surfaces to receive incident light can be formed in a single step, leaving a partially bounded fluidic region that can then be covered to provide a channel that is bounded along a length yet open at its ends; other fluidic, electrical, and optical components can also be attached.