This deliverable presents the initial version of the MUSA IDE for the security-aware design of multicloud applications. More particularly, the document describes the MUSA Modeller which supports the modelling of multi-cloud applications taking into account their security concerns. The MUSA Modeller enables: (a) the multi-cloud secure application components design and (b) embedding the security needs inside the application software following a non-intrusive approach. The document is the technical report that accompanies the actual initial software prototype of the MUSA IDE that has been designed and developed following the architecture and implementation described herein. Note that the initial version of the MUSA SLA Generator that supports the SLA specification and composition of security requirements together with functional needs was already described in deliverable D2.1.