Simplify3D does make a good support, but that's sometimes just not good enough. When creating parts that almost exceed the capabilities of the printer we use, sometimes the only way to succeed is to design the support structures on our own along with the part itself.
It works, but it's a lot of extra work. The example attached is a breathing 'valve' to a model car fuel system. The filter part is overall 37 mm long, diameter is 22.7 mm. In this case designing the support structures actually took more time than creating the part itself.
It would be a great help if - in case of a multi-body stl file - the selected bodies could be marked as 'support', and S3D could handle them as support structures.
best regards
Miklos
Sorry, I couldn't upload the stl file, its larger than 3Mb