Fabrication of sub-THz slow wave structures usually requires expensive high precision equipment. A low cost fabri- cation method for the double corrugated waveguide at sub-THz frequencies is proposed. The use of the precision cutting machine permits to quickly produce square pillars with dimensions in the range of hundreds of microns or smaller with good precision. A double corrugated waveguide has been simulated at G-band (275 - 305 GHz) with the geometry modification to keep into account the cutting profile produced by the cutting wheel. A first sample of pillars with cross section 70 x 70 microns by using the precision cutting has been demonstrated. The preliminary results are promising making the process a possible alternative to CNC milling or UV-LIGA.