KANGAROO2 Circle Packing - Different sized circles

It’s true that the topic of ‘circle packing’ actually covers a huge range of different topics. I’ve been trying for a while now to write a comprehensive guide to circle packing with Kangaroo, but there are just so many variations.
Ken Stephenson has focused most of his research career on circle packings and written a whole book on it, and that’s mostly on a quite specific mathematical definition of what constitutes a circle packing, whereas typically designers use the term in an even broader sense to refer to all sorts of approximate packings.

That said, here the discussion that Joseph links to above probably does contain the key component you need:

The custom ‘SphereCurveCollide’ goal in that definition lets you collide different sized spheres with a boundary without having to make a separate offset curve for every radius.