For those of you contemplating making a reed organ with harmonica reed
plates, why stop short of fully chromatic.  The Lee Oskar company sells
replacement reed plates for their harmonicas which are available from
your local music store for about $20 each.  I discovered that if you
select two specific sets you almost have it.

The Melody Maker G set gives in increasing pitch:

  Blow-C,E,A,C,E,G,C,E,G,C;  Draw-D,G,B,D,F#,A,B,D,F#,A

The Major Diatonic D-flat set gives in increasing pitch:

  Blow- C#,F,G#,C#,F,G#,C#,F,G#,C#;  Draw- D#,G#,C,D#,F#,A#,C,D#,F#,A#

This gives three octaves plus two notes but is missing three notes, the
first F#, first A# and last B.  There are five duplicate notes at the
first G#, second C, second F#, third C, and last F#, three of which can
be tuned to fill in the missing notes.

I suggest that you lay out the four reed plates in a spread sheet to
better see what is happening.  You should also be aware that the tuning
reference frequency is 441+ Hz.  Lee Oskar also sells a tool kit for
reed adjustment.

Ron Perry
San Diego, CA