Extraordinary long lifecycles of many scientific applications commonly surpass multiple generations of Grid technologies. Therefore the smooth adaptation and migration to newer environments remains as interesting research question. This paper presents the Otho Toolkit for synthesis of application-specific Grid service wrappers based on specifications of scientific legacy programs. The services are customised and tailor-made for a specific application, service hosting environment and computational infrastructure and include source code for optional manual refinement. We demonstrate its unique combination of advanced features like support for multiple service platforms, parameter sweeping, iterative and parallel programs, progress-reporting, filestaging and security credential management. Moreover our services reliably identify program termination-causes based on programmatically evaluated post-mortem program states. We applied the Otho Toolkit recursively to itself to synthesise a sophisticated Factory service that creates application-specific Grid services on-demand^1.