Machining mmWave Radar Rotary Couplers at 122 GHz - is it possible in a home shop?

Can I machine a tiny waveguide coupler to connect a millimetre-wave 122 GHz Radar chip to equipment and antennas fitted with waveguide flanges, whilst allowing free rotation during cavity size adjustment? Will I be able to find a simple mechanical solution that I can manufacture using my ancient manual machine tools? It’s harder than I imagined. Lots of precision machining to create a UG-387/U mmWave waveguide flange and 2mm diameter waveguide guide on my Colchester lathe and Bridgeport milling machine. As usual, there’s lots of “help“ from my AI assistant Aimee, mostly pointing out my inadequacies as a machinist so the trolls don’t need to bother. Marvellous. The design of the coupler is based on those by Andrew Alexander VK3CV to fit the Silicon Radar TRA120 mmwave chips with antennas integrated on to the device substrate. Feeds and speeds for the brass machining section: 900 rpm using the variable speed 3 phase inverter, feed mm per rev, CZ121 bar. Insert