Electrical treeing (ET) is a stepwise dielectric breakdown process that generates a branched, hollow network of tubules in the dielectric between the electrode and ground. In this study, the controlled growth of electrical trees (ETs) in epoxies is demonstrated as a technique for fabricating synthetic vascular systems in engineering materials. A number of experimental conditions are explored, including AC versus DC voltage and geometric arrangement of the electrode and ground. AC growth tends to induce highly branched, “bush-like” trees while DC growth tends to produce lower-order branched structures. In addition, treating electrode surfaces with multi-walled carbon nanotubes (MWCNTs) is shown to promote ET initiation, most likely due to enhancements in the local electric field intensity. The utility of these structures for vascular applications is demonstrated by filling the channels with dyed liquids.