The Persian ney is made out of a piece of Arundo Donax, a bamboo-like grass. A piece is selected containing seven segments, which defines the length of the ney. Conditions must be just right to procude the right thickness and length. For this a hot dry climate such as in the area's south of Esfahan Iran is needed. The cut piece is dried for several years, and cleaned out, and 6 holes are burnt in it at the right spots. It has been said that only 1% of the neys produced this way actually sound good, so it is a time consuming process despite the simplicity of the instrument.
It is also possible to make a ney out of other materials, with excellent results. I've made some neys out of PVC and acrylic pipe which are as good as a nice cane ney, though not quite as good as the best neys I have.
The best materials I found so are:
_ _ | | | | | | | | | | | | | | | | | | | | | | | |file to something like:
| | /\ || || 1cm (approximately) | \ / | \/ | | | | | | | | | | | |Now take a cylindrical piece of steel (I use the back of drill bits) of diameter 9mm and heat it up over a candle. Make it hot enough to melt, but not burn the plastic. Melt in the finger-holes of the ney with this.
Alternatively you can use a "Forstener drill bit", made especially for making circular holes, for use with a power drill. For the acrylic this works better.
Heat the ney gently above the candle, at the area 48mm from the top, rotating the ney above the candle. When the area becomes slightly soft, take a piece of cord (not too thin, or you will cut the pipe), wind it around the hot area, and tighten it, making a notch with inside diameter slightly larger than the finger-holes. This is to imitate indentations where the side branches on the cane are. Do this at places 48mm, 172mm, 289mm, 396mm, 504mm, 595mm from the top.
The last thing to do is to widen the top. I do this by warming the top over a candle, and pushing a cone shaped metallic thingy in (about 2-3cm), thereby stretching the ney. I do this several times, until the top is a little wider than the rest. In the end you can insert the bottom of a the unstretched pipe into the top, very tightly. This last step improves the sound a lot. A better way to do this exists but I have not discovered it. If you do, let me know. (A hint: use a "taper pin" and a "tapered reamer".)
This ney plays in Bb (B flat). You can scale the length, to make neys in different keys. If interested, ask me for measurements from neys in other keys. They scale approximately linear (i.e., all proportions remain the same), but not completely. Smaller neys than C don't play well in the upper register. The longest ney I've made is F (C-kuk).
Below are measurements of several neys. Keep in mind the lengths can vary by about 1 cm depending on the inside structure. Narrower nodes give a lower pitch, smaller fingerholes give a lower pitch too.