Regarding Tim Baxters wanting to play notes in the expression hole
range on the Duo-Art here's a trick that can be used at the bass and
of the range.

It's called synthetic or accoustic bass.  It is accomplished merely by
sounding the octave of the tone you want along with the tone a fifth
interval above that.  It is a trick that was often used in pipe organs
and I've used it in piano rolls on occasion, too.

Hal Davis