  Autonomous quantum thermal machines do not require an external coherent drive
or work input to perform the desired tasks, which makes them a promising
candidate for thermal management in quantum systems. Here, we propose an
autonomous quantum thermal machine in which two uncoupled macroscopic
mechanical resonators or microwave resonators achieve considerable entanglement
via a hot thermal bath. This becomes possible by coupling the resonators to a
common two-level system or third harmonic oscillator and driving it by the hot
incoherent thermal bath. The critical step to make the entanglement involves
suitable engineering of the hot bath, realized by bath spectrum filtering. Our
results suggest that the bath spectrum filtering can be an alternative to
typical non-autonomous reservoir engineering schemes to create exotic quantum
states.
