A cradle jig comes in handy during hollowing and base-bar fitting.  I managed without one up until now, but decided it was time.  I based this one on pictures from Courtnall.  Its made to accommodate deep (high) arching, adjustable length (up to large violas), and interchangeable blocks.  The wood is poplar, the adjustment knob is an old piece of ebony, all unfinished at this point.