A hollow turbine engine component with complex internal features can include a first region (120) and a second, high resolution region (124). The first region (120) can be defined by a first ceramic core piece formed by any conventional process, such as by injection molding or transfer molding. The second region (124) can be defined by a second ceramic core piece formed separately by a method effective to produce high resolution features, such as tomo lithographic molding. The first core piece (12) and the second core piece (14) can be joined by interlocking engagement that once subjected to an intermediate thermal heat treatment process thermally deform to form a three dimensional interlocking joint (132) between the first and second core pieces (12, 14) by allowing thermal creep to irreversibly interlock the first and second core pieces (12, 14) together such that the joint (132) becomes physically locked together providing joint stability through thermal processing.