New morphological drainage domain?

[kbruning]

Could a new morphological drainage domain type be created that consists of an array of spheres inside of a cylindrical capillary tube? For example includes:

1. a cylinder centered at (x=1,y=1) with radius of 3 and height (z) = 5
2. spheres at the following x,y,z,r:
   0 0 3 1
   2 0 3 1
   2 2 3 1
   0 2 3 1

This could all be shifted over to be centered at 0,0 instead of 1,1. Ideally, I would like to be able to modify the radius and height of the cylindrical tube, and input an arbitrary but small array of spheres to go inside of it. The spheres would never touch or cross the cylindrical tube boundary wall.

Thanks!