As a tool helping to interpret diffuse X-ray emission of PNe, and as a supplement to our RHD simulations, we have started to construct a grid of theoretical X-ray spectra of wind-blown bubbles with temperature and density profiles according to thermal conduction theory. We investigate how the X-ray spectra depend on chemical composition (e.g. H-rich vs. H-deficient) and how temperature and abundance determinations reflect gradients of temperature and chemical composition within the bubbles. These synthetic models shall allow to quickly perform detailed parameter studies without the need for dedicated hydrodynamical simulations. We report on ideas and goals.