Any-phone Arm Band

So i have been dreaming of this design for a while, but certain parts are still left to conquer. Hopefully someone out there can help. I have provided the OpenSCAD model in order to speed things up. Its \\"parameterized\\" so you simply change variable values and you get a whole new container!

The concept here is that the object is printed with the right size and spec to your phone. You then cut and sew together an elastic band. Let it be known that i do not have any real prior experienc