Hi Heiner, as you get to shapes that are not very well defined by 2D profile curves they can be difficult to create with CAD toolsets and often times polygon modeling toolsets are a better match for things like that.

It looks like you already have this modeled in polygon form - why is it that you're trying to model it again in MoI ?

You might instead want to look at t-splines or nPower sub-d NURBS conversion tools which can convert an existing sub-d model into NURBS form, if you're trying to get your polygon model into something like SolidWorks for example.

-Michael