  In this work a new numerical technique to prepare Cauchy data for the initial
value problem (IVP) formulation of Einstein's field equations is presented.
Directly inspired by the exterior asymptotic gluing (EAG) result of Corvino
(2000) our (pseudo)-spectral scheme is demonstrated under the assumption of
axisymmetry so as to fashion composite Hamiltonian constraint satisfying
initial data featuring internal binary black holes (BBH) as glued to exterior
Schwarzschild initial data in isotropic form. The generality of the method is
illustrated in a comparison of the ADM mass of EAG initial data sets featuring
internal BBHs as modelled by Brill-Lindquist and Misner data.In contrast to the
recent work of Doulis and Rinne (2016), and Pook-Kolb and Giulini (2018) we do
not make use of the York-Lichnerowicz conformal framework to reformulate the
constraints.
