Companies like GE, SAP, Mathworks, Dassault, PTC and Siemens all have digital twin platforms used by major manufacturers. Initially there was a period (2003 -2013) where twin systems were built my specialist media developers using 3rd party authoring tools and integrating with different system simulation tools. While this still happens for specialist or niche projects (or sometimes on very large projects with specific deadlines that require outsourced help). Increasingly most manufacturers build digital twins directy from design assets (CAD, CAM, Systems simulations etc) as part of the in-house product development process using extensions to their existing design and simulation tooling.