Generally, my advice would be to think of your ideal
garden bed, only in rings. So you want to be able to comfortably sit or kneel in the paths to work on a bed on either side (and this will be dictated by the largest person who will be doing such work), and you want to be able to reach at least halfway across the beds without straining your back. This last distance will vary based on the smallest person expected to weed or mulch or harvest, and or the person with the least flexibility/strength/mobility. Generally the beds will be under four feet wide, and the paths around two feet wide, but... it depends on the people doing the work.
Too big of a
project and getting into the mandala will be a chore. You probably want to keep it smaller rather than larger. I'm thinking 5 rings or less unless you are ringing it with a shelterbelt hedge or fedge (food hedge) then that could maybe be one more an that one might be a lot wider as you will be standing or using a ladder to work on it.
I wouldn't use wattle (which seems to me to bring to mind woody branches---which might be alright buried deeply under the beds like hugulkultur). What I would do is simply build up materials on top of the newspaper that you would like to grow food in, such as
straw, hay, leaves, soil,
compost, etc.
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