  Folding mechanisms are zero elastic energy motions essential to the
deployment of origami, linkages, reconfigurable metamaterials and robotic
structures. In this paper, we determine the fate of folding mechanisms when
such structures are miniaturized so that thermal fluctuations cannot be
neglected. First, we identify geometric and topological design strategies aimed
at minimizing undesired thermal energy barriers that generically obstruct
kinematic mechanisms at the microscale. Our findings are illustrated in the
context of a quasi one-dimensional linkage structure that harbors a
topologically protected mechanism. However, thermal fluctuations can also be
exploited to deliberately lock a reconfigurable metamaterial into a fully
expanded configuration, a process reminiscent of order by disorder transitions
in magnetic systems. We demonstrate that this effect leads certain topological
mechanical structures to exhibit an abrupt change in the pressure -- a bulk
signature of the underlying topological invariant at finite temperature. We
conclude with a discussion of anharmonic corrections and potential applications
of our work to the the engineering of DNA origami devices and molecular robots.
