  We show that if the solutions to the (2+1)-dimensional massless Dirac
equation for a given 1D potential are known, then they can be used to obtain
the eigenvalues and eigenfunctions for the same potential, orientated at an
arbitrary angle, in a tilted anisotropic 2D Dirac material. This simple set of
transformations enables all the exact and quasi-exact solutions associated with
1D quantum wells in graphene to be applied to the confinement problem in tilted
Dirac materials such as borophene. We also show that smooth electron waveguides
in tilted Dirac materials can be used to manipulate the degree of valley
polarization of quasiparticles travelling along a particular direction of the
channel. We examine the particular case of the hyperbolic secant potential to
model realistic top-gated structures for valleytronic applications.
