Z-Suite v1.8.2 distortion

It looks like the Z-Suite V1.8.2 program is modifying the model that was loaded as a  .STL file.  I hope that the two figures that I attached are visible.

The first figure is what is loaded into the Z-Suite program and the second one is the result of clicking  > Print.

The second figure looks shallow compare to the original one. The cross-section of the original model is a semi-circle. 

I'll appreciate if someone can tell what's going on.  The .stl file in english units is also attached. Thanks.4176

Walls are too thin

f5db50b3e9574b8daaa21780ce1dc5d3.png

That was it. Thank you Marcin. Now I have to find the minimum thickness that will work, in order to save filament.