  We study the relationship between fibered ribbon 1-knots and fibered ribbon
2-knots by studying fibered slice disks with handlebody fibers. We give a
characterization of fibered homotopy-ribbon disks and give analogues of the
Stallings twist for fibered disks and 2-knots. As an application, we produce
infinite families of distinct homotopy-ribbon disks with homotopy equivalent
exteriors, with potential relevance to the Slice-Ribbon Conjecture. We show
that any fibered ribbon 2-knot can be obtained by doubling infinitely many
different slice disks (sometimes in different contractible 4-manifolds).
Finally, we illustrate these ideas for the examples arising from spinning
fibered 1-knots.
