Help with copy of real model

Hello I would like ask how draw this three imaginary round objects to each other please ? Ring + concave bottom and middle sphere.

And the also back side which hollow shape. Please do you have some idea or tutorial similar.

Many thank you. Ondrej -

This would be ideal for drawing a cross section of the shape, then revolve it around the center axis.

Here is a quick video of a similar shape, to show concept of the methodology. iCloud

Perfect idea. Thank you. But how you draw this irregular curves please?

I drew those using the Spline tool, then used Offset to create the parallel line. I then connected the ends, to close the shape.

Hello. This is my result. Thank you for help. Ondrej


Great job!