This paper discusses use of octree based voxel model for representation of spatial conflicts across multiple design domains. A framework has been developed to create octree based voxel model linked with intended empty spaces in product, which are associated with design requirements, product lifecycle states and connected design domains. Knowledge in System Modelling Language (SysML), is used to select criteria for building octree voxel model. A case study of Coupled cavity travelling wave tube (CCTWT) Slow Wave structure (SWS) design has been taken to showcase the code capabilities. Octree voxels inside CAD platform show and represent spatial conflicts, detected by associativity modelling of Empty space blocks inside CAD along with the Product knowledge in SysML model.