mating non linear shapes

hey there does anyone know how to mate non linear shapes like two
spheres ?

 

There is a tangent mate. It doesn't work on all double curved
surfaces. For example mating a cylinder and toroid doesn't seem to
work.

 

what's a toroid?

 

what's a toroid?

 

Donut.


Depending on the complexity of the shape, reference planes are
generally a good way to go when you can't mate directly to geometry.

 

Everything you ever wanted to know about toroids:

http://mathworld.wolfram.com/Torus.html

In particular I was speaking of the Ring Torus.