  We have developed our original made-to-measure (M2M) algorithm, PRIMAL, with
the aim of modelling the Galactic disc from upcoming Gaia data. From a Milky
Way like N-body disc galaxy simulation, we have created mock Gaia data using
M0III stars as tracers, taking into account extinction and the expected Gaia
errors. In PRIMAL, observables calculated from the N-body model are compared
with the target stars, at the position of the target stars. Using PRIMAL, the
masses of the N-body model particles are changed to reproduce the target mock
data, and the gravitational potential is automatically adjusted by the changing
mass of the model particles. We have also adopted a new resampling scheme for
the model particles to keep the mass resolution of the N-body model relatively
constant. We have applied PRIMAL to this mock Gaia data and we show that PRIMAL
can recover the structure and kinematics of a Milky Way like barred spiral
disc, along with the apparent bar structure and pattern speed of the bar
despite the galactic extinction and the observational errors.
