Hi Matadem, the curves to sweep in your attached file are not suitable for making a solid just by themselves. It would be too thin at the ends and be essentially the same as a self intersection in those areas.

To incorporate this into the main model you would sweep to build just a surface and then trim away surrounding areas to make a place to join it in.

I've done that with the model that I attached in the above post here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=10586.14

Was that finished solid that I posted there not suitable for what you need?

- Michael