Were you drawn to the Teracube 2e for it's ecological stance?  Or for the fact that it will remain relevant with Android updates for 3 years and still be under warranty for 4 years?  That's impressive for a modern smartphone.  With a phone that can last that long, you'll want to take good care of it with a sturdy protective cover.  Why not choose one that is also distinctive and one that shares some of the qualities that perhaps brought you to the Teracube such as being made sustainably with natural materials and by crafts-people who are paid a living wage right here in the US.