  We outline the concrete steps involved in building prescriptive master
integrand bases for scattering amplitudes beyond the planar limit. We highlight
the role of contour choices in such bases, and illustrate the full process by
constructing a complete, triangle power-counting basis at two loops for six
particles. We show how collinear contour choices can be used to divide
integrand bases into separately finite and divergent subspaces, and how
double-poles can be used to further subdivide these spaces according to
(transcendental) weight.
  Complete details of the basis constructed for six particles is provided in
the ancillary files for this work's submission to the arXiv.
