To fully exploit the potential of cloud computing, design and development of cloud applications should be eased and supported. The OASIS TOSCA standard enables developers to design and develop cloud applications by specifying their topologies as orchestrations of typed nodes. However, building such application topologies often results in reinventing the wheel multiple times when similar solutions are manually created by different developers for different applications having the same requirements. Thus, the reusability of existing TOSCA solutions is crucial to ease and support design and development processes. In this paper, we introduce and assess ToscaMart, a method that enables deriving valid implementations for custom components from a repository of cloud applications. The method enables developers to specify individual components in their application topologies, and illustrates how to match, adapt, and reuse existing fragments of applications to implement these components while fulfiling all their compliance requirements. We also validate ToscaMart by means of a prototypical implementation based on an open source toolchain and a case study.