In an analogy to the neutron, which decays rapidly as a free particle, but when bound in a nucleus it is stable, would it be possible to crease a structure that permits the stability of muons - be it muonic atoms, some sort of muonic lattice, etc.?
Granted, the energetic benefit of the neutron $\beta$ decay is only about 0.08% of its rest mass, while the muon is roughly 200 times as massive as the electron, thus having much more to gain from decaying - making this proposition seem somewhat unlikely.