Hi MrBraun, MoI does not yet have a tapered extrusion function.

But you can probably get the result you need by doing a combination of Offset, then moving the offset result in the Z direction, and then Loft. Those are actually the same steps that a tapered extrusion would do internally.

Please see this previous post for an example:
http://moi3d.com/forum/index.php?webtag=MOI&msg=941.5

If you have any difficulty with your particular shape, could you please post the curves so I could take a look?

- Michael