Reticulum.
Recently, Zentangle released a Kitchen Table video that featured using Tripoli as a Reticulum (as the underlying structure) and filling each section with a fragment. I chose Fragment G13 from the Primer. I have never liked Tripoli until now! But I will not discount it in the future. This gave me a really good understanding of Reticula and Fragments.
Zentangle drawn on Strathmore Vellum Bristol using a black, Micron pen. Shading done with graphite pencil.