A novel manufacturing strategy for the detailed fabrication of complex and mechanically robust microwave components is presented. Additive printing of the full wax positive model with a multijet printer allows free shaping on the one hand, while metal casting provides mechanical stability for a variety of applications on the other. In addition to that a slotted waveguide model is used to improve the post-processing and performance. This combination is used with a rectangular waveguide for the E-band to demonstrate the performance of this manufacturing method at higher frequencies than previous publications. Measurements on the samples show comparable attenuation coefficients to the milled split-block counterpart, i.e., less than 5dB/m, a good root mean square (RMS) surface roughness of the inner surfaces with $S_{\textrm {q}}$ = $5.85\; {\mathrm { \mu \text {m} }}$ and astonishingly fine tolerances of 8.8±40.3 ${\mathrm { \mu \text {m} }}$ overall. Comparisons are also made between other published additive manufacturing processes.