  Kagome metals exhibit rich quantum states by the intertwining of lattice,
charge, orbital and spin degrees of freedom. Recently, a novel charge density
wave (CDW) ground state was discovered in kagome magnet FeGe and was revealed
to be driven by lowering magnetic energy via large Ge1-dimerization. Here,
based on DFT calculations, we show that such mechanism will yield infinitely
many metastable CDWs in FeGe due to different ways to arrange the
Ge1-dimerization in enlarged superstructures. Intriguingly, utilizing these
metastable CDWs, innumerable polymorphs of kagome magnet LiFe6Ge6 can be
stabilized by filling Li atoms in the voids right above/below the dimerized
Ge1-sites in the CDW superstructures. Such polymorphs are very stable due to
the presence of magnetic-energy-saving mechanism, in sharp contrast to the
non-magnetic "166" kagome compounds. In this way, a one-to-one mapping of the
metastable CDWs of FeGe to stable polymorphs of LiFe6Ge6 is established. On one
hand, the fingerprints of these metastable CDWs, i.e., the induced in-plane
atomic distortions and band gaps, are encoded into the corresponding stable
polymorphs of LiFe6Ge6, such that further study of their properties becomes
possible. On the other hand, such innumerable polymorphs of LiFe6Ge6 offer
great degrees of freedom to explore the rich physics of magnetic kagome metals.
We thus reveal a novel connection between the unusually abundant CDWs and
structural polymorphism in magnetic kagome materials, and establish a new route
to obtain structural polymorphism on top of CDW states.
