Concentric circles

[Krikor]

Another option to achieve this result is Ottia Tuota's plugin - 'Replicate path by affine mapping'.
The plugin should be at the link http://kmarkku.arkku.net/Path_replicate_...aster.html

You create the first path-circle with a diameter of 600 px, then create the second path-circle with a diameter of 598 px (or if you prefer, use the Scale tool).
Then apply the plugin and indicate the number of copies desired, in this case 120 copies.

The plugin will generate the 120 concentric copies.
   
The hardest part will be applying a border to each path one by one.
   

Edited:

A small oversight on my part.

Using ofn-stroke-fill-path the process of creating borders for each path is done in the blink of an eye!