  We have used an electromigration technique to fabricate C$_{60}$-based
single-molecule transistors. We detail the process statistics and the protocols
used to infer the successful formation of a single-molecule transistor. At low
temperatures each transistor acts as a single-electron device in the Coulomb
blockade regime. Resonances in the differential conductance indicate
vibrational excitations consistent with a known mode of C$_{60}$. In several
devices we observe conductance features characteristic of the Kondo effect, a
coherent many-body state comprising an unpaired spin on the molecule coupled by
exchange to the conduction electrons of the leads. The inferred Kondo
temperature typically exceeds 50 K, and signatures of the vibrational modes
persist into the Kondo regime.
