Jurgen Goering asked for experiences in reed making.  Here are mine.

I used plain unspecified brass sheet from the hardware store; available
dimensions were 0.2, 0.5, and 1 mm thickness.  For a rank of pipes you
need reeds of graduated thickness, different for every note.  I found
it good to use the rule that thickness should be 0.025% of lambda, the
fundamental wavelength in air.  This makes 0.8 mm for A=110 Hz, 0.4 mm
for a=220 Hz, etc.  It is no small enterprise to do this with hand
tools, but it can be done.

The necessary outfit is: plate shears, anvil in form of a flat ground
steel block, polished hammer, flat file, screw micrometer, propane
torch, and support jigs for filing.

Cut a blank with the shears.  Length will have to be some 3% of lambda.
Width is more problematic, perhaps 12 mm for A=110 Hz, decreasing much
more slowly with frequency, maybe to 6 mm for a''=880 Hz.

Brass (like copper and silver) becomes soft and easily pliable and
malleable when annealed.  Heat it to dark red, perhaps 500 deg C, with
the torch and let it cool.  After cold rolling or hammering it becomes
hard and springy again, when the thickness has decreased 1 or 2
percent.  For professional work you have to invest in a rolling mill,
otherwise you can learn to hammer it thinner against the anvil.

It takes lots of practice to give hard and well distributed blows, and
_never_ hit with the edge of the hammer -- the reed will harden and
become slightly concave.  Turn it and go over the other side, then
check with the micrometer.  Once it's hard you must anneal it with
the torch before you proceed hammering again, otherwise it will crack
sooner or later.  To reduce thickness to half the original may easily
take 20 rounds of annealing and hammering.

When down to about 0.03 mm over the desired thickness you may still cut
the reed into shape with the shears.  Now do a final hammering to make
it as hard and as flat as possible.  After this point no more annealing
and no cutting -- only filing is legal, and then be careful to support
the reed in order not to bend and deform it.

For flat filing you can support the reed on a plate clamped to the
table.  An angle of thin tin plate strips, soldered or glued to the
support, prevent the reed from sliding.  It is tedious work to file
away the hammer marks on both sides and get constant thickness to
within +/- 0.01 mm.

If this kind of work appears too intimidating I suppose you will have
to try organ suppliers like www.laukhuff.de.

Johan Liljencrants