SPASE 3.0 is the next generation of the SPASE metadata format for Heliophysics. Its development is driven by the need to increase support for FAIR principles and solve difficulties with creating and managing SPASE resources. A set of space and solar physics use cases for using SPASE model with the Heliophysics-wide search interface, as the SPASE model main function, were proposed and voted on by members of the international Heliophysics community. The use cases include both the original set of use cases and an additional set based on the fundamental functionality of the SPASE model current version not captured in the original use cases. The accepted use cases were used to extract functional requirements for the SPASE 3.0 model. We discuss the functional requirements, a draft SPASE 3.0 model design with resource description examples, and improvements over the SPASE model current version.