I am working on an idea I had for our science museum and I think I just
ran out of steam.  I'd like to design an exceedingly simple mechanical
musical instrument for the guests to program, or even build.  Here are
the constraints.  They seem to me to be mutually-exclusive, but perhaps
someone can help:

1. Cheap, but only for instruments that the guests themselves would
build and take home.

2. Crude enough for even the likes of me to build.  My skills include
sheet-rock screws, wood glue, hole-drilling, and sufficient creativity
in designing to avoid having to have any real skills.

3. obvious in operation.  This excludes electronics and conventional
player-piano actions, though plain amplification would be okay.
Pneumatic mechanisms should be reasonably okay.

4. Sturdy enough to survive a certain amount of abuse from
five-year-olds.

The device would _not_ have to have the following:

1) Beauty;

2) Lots of notes; maybe a fifteen-note major scale;

3) Polyphonic capability like a music box or player piano; there's no
real need for chords;

4) Low noise level: it can clatter and clank, as long as we can hear
the notes;

5) Elegant mechanical design;

6) Power-cord independence: a vacuum cleaner motor or air compressor
is perfectly permissible;

7) Light weight; it will have to go on wheels, but they can be very
sturdy wheels.

I started thinking about this whole enterprise when I read the post
about the little train that plays a tune by hitting its xylophone-bar
ties.  I'm utterly incapable of building such a thing, and the bars
themselves might be a challenge.  But I can see a sort of proto-barrel
piano that uses tubular chimes made of steel electrical conduit (the
tuning shouldn't be too tough) or even a very long xylophone supplied
with lots and lots of these tubular chimes laid in a long row to be
played in sequence by hand.

The barrel piano is attractive because it uses only fifteen or so
chimes; the sequential device would need lots of them.  But the
mechanical parts of the sequential-bar instrument would be minimal.

I've mentioned the possibility of having kids build some sort of MM
instrument themselves.  I gave this some thought several months ago
when someone asked for advice on the subject in MMD.

What I came up with at the time was a tin whistle -- the sort with
eight holes, I think -- in which the holes are blocked or opened by
means of a punched paper tape, or belt, stretched around the body of
the flute with a half turn.  The flute would be fixed in some sort of
clamp, and in a perfect world the holes would be covered or uncovered
sequentially as the kid, or an air pump, blew through the mouthpiece.
This sounds impossible even as I write it, but perhaps there's room
for thought on this.

Other ideas come to mind:

1. Find a music box movement -- we're talking minimal Sankyo here --
with an electric motor.  Optically magnify it so people can see how it
works, and amplify its reeds with a guitar pickup.

If this seems far too elementary -- I mean, who doesn't know how a simple
music box movement works? -- let me assure you that our patrons, and
lots of your friends and relatives do not, and would be fascinated.

2. Find a toy piano and somehow fit a barrel to it.  This might be the
simplest alternative if there's still such a thing as a toy piano
anywhere.

The problem with this last, and any of the barrel schemes, is that the
barrel must be programmed with a suitable arrangement.  I'm afraid that
I've ignored posts about arrangements for such instruments: apparently
people are able to make up their own (a task inconceivable to me) and
even develop software to do the job.

I'm also not so keen on making a barrel, or drum.  Right now, The Great
Craftsman Kinsler is considering finding a big tin can or small
lubricant drum and welding upon it a sea of threaded nuts. The teeth of
the barrel would thus be bolts threaded into the nuts.

If you've read this far, thank you and congratulations on your
persistence.  Any help, comments, or outright derision would be helpful
and appreciated.

Mark Kinsler
Lancaster, Ohio USA
http://www.mkinsler.com/