  Casimir forces from fermions in an extra dimension can stabilise
Randall-Sundrum models. Contrary to previous expectations, the stabilisation
can produce large electroweak hierarchies without fine tuning. The Casimir
stabilisation occurs in the same five-dimensional fermion models which have
been found to give the observed fermion mass hierarchies. This is shown for
masses generated by the Higgs mechanism and by a Higgsless symmetry breaking
mechanism, where new light Kaluza-Klein states are presented
