Traffic traces captured from backbone links have been widely used in traffic analysis for many years. By far the most popular use of such traces is replay where conditions and states of the original traffic trace are recreated almost identically in simulation or emulation environments. When the end target of such research is detection of traffic anomalies, it is crucial that some anomalies are found in the trace in the first place. Traces with many real-life anomalies are rare, however. This paper pioneers a new area of research where traffic traces are engineered to contain traffic anomalies as per user request. The method itself is non-intrusive by retaining the IP address space found in the original trace. Engineering of several popular anomalies are shown in the paper while the method is flexible enough to accommodate any level of traffic trace engineering in the future.