layer-line friction entirely. PETG’s slight flexibility might also introduce minor deflection under load. If smooth motion is critical, you might want to explore SLS (nylon) or MJF printing—these processes produce near-isotropic parts with tighter tolerances and no layer lines. That said, for a prototype or light-duty use, FDM could suffice with some trial-and-error tuning.

In terms of lubricating, yes, light lubricant will reduce friction and noise from layer lines. Just avoid oils that might degrade PETG. A tensioner is a smart backup—let me know how the test goes! If you hit persistent issues, resin printing (for higher detail) or outsourcing to SLS could be next-step options. Good luck!