  Abridged for arXiv: In this work, we apply a powerful new technique in order
to observationally derive accurate assembly histories through a self-consistent
combined stellar dynamical and population galaxy model. We present this
approach for three edge-on lenticular galaxies from the Fornax3D project -- FCC
153, FCC 170, and FCC 177 -- in order to infer their mass assembly histories
individually and in the context of the Fornax cluster. The method was tested on
mock data from simulations to quantify its reliability. We find that the
galaxies studied here have all been able to form dynamically-cold (intrinsic
vertical velocity dispersion $\sigma_z \lesssim 50\ {\rm km}\ {\rm s}^{-1}$)
stellar disks after cluster infall. Moreover, the pre-existing (old) high
angular momentum components have retained their angular momentum (orbital
circularity $\lambda_z > 0.8$) through to the present day. Comparing the
derived assembly histories with a comparable galaxy in a low-density
environment -- NGC 3115 -- we find evidence for cluster-driven suppression of
stellar accretion and merging. We measured the intrinsic stellar
age--velocity-dispersion relation and find that the shape of the relation is
consistent with galaxies in the literature across redshift. There is tentative
evidence for enhancement in the luminosity-weighted intrinsic vertical velocity
dispersion due to the cluster environment. But importantly, there is an
indication that metallicity may be a key driver of this relation. We finally
speculate that the cluster environment is responsible for the S0 morphology of
these galaxies via the gradual external perturbations, or `harassment',
generated within the cluster.
