For those who want to know more about regarding Dunedain design, it's going to be halfway between Aidan Meehan and Zentangle.
About 25 years ago a guy named Aidan Meehan wrote "Celtic Design: Knotwork: The Secret Method of the Scribes" a book that concisely laid out the rules of celtic knotwork, and proposed simple methods to replicate even the most complex patterns.
Additionally I have, of late, been forced to participate in a weekly zentangle group
. Which is another method of building up complex patterns from simple shapes.
Anyway, when I started looking at the Numenorean design motifs I started realizing that they use about 6 standard repeating patterns, which should be straight forward to decode and set out for use.
I'll probably also pull some stuff from the Fr. Christmas letters, as there are strong similarities between some of the borders and NPB's Goblin script. ( I'll note when I pull in non-Dunedain material. )