Hi Andrei, could you maybe describe a bit more about what result you're looking for?

If you want a sphere, the easiest way to do that is to use Draw solid > sphere to make the sphere - if you want something to deform onto a sphere, you can create a sphere by drawing it and then use it as the target surface for flow.

The "manual" way to make a sphere is to draw a 180 degree arc and then use Revolve on it.

Flow works by deforming objects from a base surface onto a target surface, you usually will not create a primitive shape using flow, you build a simple target surface using other tools like drawing a sphere or revolve or sweep, etc... and then that surface can be used for generating the flow deformation.

If you're trying to generate a second sphere by doing flow of a second plane onto an already existing sphere, that can be problematic since a sphere contains "pole" areas where the surface compresses down to a single point. Areas like that where there is not a clear "unique one to one" relationship between each surface (not _unique_ one to one since many points along one edge of the plane do not map to independent points on the sphere, they all map to the same pole point), can make for an inconsistent transformation. For things like that make second plane, the one that you're trying to transform to be slightly shorter than the base surface so that it will not try to transform surface area onto the pole point of the sphere.

- Michael