  We propose an extension of the Standard Model (SM) based on the
$SU(3)_C\otimes SU(3)_L\otimes U(1)_X$ (3-3-1) gauge symmetry and scale
invariance. Maintaining the main features of the so-called 3-3-1 models, such
as the cancellation of gauge anomalies related to the number of chiral fermion
generations, this model exhibits a very compact scalar sector. Only two scalar
triplets and one singlet are necessary and sufficient to break the symmetries
dynamically via the Coleman-Weinberg mechanism. With the introduction of an
Abelian discrete symmetry and assuming a natural hierarchy among the vacuum
expectation values of the neutral scalar fields, we show that all particles in
the model can get phenomenologically consistent masses. In particular, most of
the standard fermion masses are generated via a seesaw mechanism involving some
extra heavy fermions introduced for consistency. This mechanism provides a
partial solution for the fermion mass hierarchy problem in the SM. Furthermore,
the simplicity of the scalar sector allows us to analytically find the
conditions for the potential stability up to one-loop level and show how they
can be easily satisfied. Some of the new particles, such as the scalars $H$,
$H^\pm$ and all the non-SM vector bosons, are predicted to get masses around
the TeV scale and, therefore, could be produced at the high-luminosity LHC.
Finally, we show that the model features a residual symmetry which leads to the
stability of a heavy neutral particle; the latter is expected to show up in
experiments as missing energy.
