Webs give a diagrammatic calculus for spaces of SL(r)-tensor invariants, but intrinsic characterizations of web bases are only known in certain cases.
In recent joint work with Christian Gaetz, Oiver Pechenik, Jessica Striker and Joshua Swanson we have introduced hourglass plabic graphs as a new avatar of webs to give the first rotation invariant SL(4)-web bases.
In this talk I will discuss a construction that produces an hourglass plabic graph from a non-crossing partition and its Kreweras complement, which recovers Chris Fraser's rotation-invariant web basis for Plücker degree two representations of arbitrary SL(r).