There are classic rules of thumb used in buy/build decisions. Buy in situations of parity. Build for competitive advantage/differentiation. In a buy scenario, you willingly cede control of the end product (functionality, architecture, technology) for the promise of a lower price tag, ease of implementation, and quicker time to market. For success, you must actually cede that control—in other words, no modifications. But, that’s not always realistic. So, how can you reap the advantages of a buy, while providing a solution that actually fits your business (modifications and extensions), without getting trapped? Think vanilla layer cake.