PETG works great, but you can use other materials as well. If you happen to have a spool of (pure) nylon sitting around, go for it. Generic settings for 0.4n and 0.2l work great, just increase the number of perimeters to ≥3. Print as-is and fold afterwards. You might need to slightly scrape the end of the arm to make it fit snugly into the sheath, depending on your printer. The .3mf file (Prusa Slicer project) includes all the required settings.
The author remixed this model.
Some heavy users were reporting a shorter lifetime, so I beefed up the arm and joint to prevent it from breaking off.