Yes, this widget is made of plastic.
Yes, this plastic is Polyurethane.
Yes, this Polyurethane is tough.
The 3D printed polyurethane that I use (Filaflex) in these springs has been tested to over 100,000 flexing cycles with no visible signs of wear :
Conclusions : https://github.com/daprice/Flexy-Joint/wiki/Materials
Testing Results : https://github.com/daprice/Flexy-Joint/wiki/Torture-Testing