I was contemplating making one, but if I encountered problems I would not know whether to blame my playing or my manufacturing…
…hence my questions 
And mine
The wall thickness of the one on the web is 2mm (FAQ page). The embouchure looked to be about half the diameter of the pipe - I roughly measured the photo!
Have you any idea wha the man means by hard/soft?
The hard version , the most powerful one, needs more breath and the distance between the fingers is bigger. I guess that a trip to the shop for a length of pipe is on the cards. One inch diameter or thereabouts for a low D. Cut a section of pipe a couple of inches too long and start playing with notches.
The soft version, a compromise between the easiness of playing and the strenght of the instrument requires less breath, sounds are easier to come out and the distance between the holes are adapted to small hands.
The hole positioning I understand - but (how) does this affect air requirements? Or is there some subtle difference in the ‘notch’?
Simple: if the holes and notch align with the third phase of Remulak in the second cycle of the first aeon, then less air is required. If, on the other hand, the holes and the notch align with the second phase - well, let’s just say you’d better check your stock of toilet paper in the shelter. You know you’ll need it.
In answer to one of the questions: I find it harder to play than flute. You have to position the air stream perfectly to get it to sound. Nice when you get the sweet spot, though.
I’m trying to make my own out of PVC pipe. In the past the fipple was the hardest part of making the Guido Low Tech whistles so this quena style really has my interest. I made my notch in my PVC tube but I’m not sure if it should be bigger or smaller. I have to below quite a bit, it seems this design would require a lot more air than a whistle, which is probably why he offers the hard & soft versions.
Any idea on how to find the idea notch size?? Should it be beveled?
Here is another topic about this low whistle on a french forum : http://whistle.xooit.fr/t2318-Open-whistle.htm
this might help a bit http://www.youtube.com/watch?v=G1zYc7B4m3E&feature=related
but still can’t get much out of mine 
That video in spanish really helped. It takes me a while but I can find the right “spot” and get a note and jumping octaves is very easy. But if I take it away from my mouth then I have a hard time finding the spot again. Will take practice.
I used a mistake tube from a low F. I just cut the window off of the F and I was very surprised that mine plays a perfectly in tune E. What are the chances of that?
So now where do I drill the holes? Guido has plans for an E. Could I use the same measurements? Using the notch as the window? I don’t mind if the first one is a bit off but I’d like to know how to measure it properly.
If you have the pipe cut to the correct length for the bell note, then simply use one of the fine pieces of software that will calculate the hole for you. Seach for ‘Flutomat’ or ‘TWCalc’, or follow the link in my signature line for the one I wrote. The downloaded version of mine has a tuner as well…
One further addition - the hole spacing is NOT tough on the fingers! In fact it’s much easier than a low-D whistle. I think my earlier comments were due to my efforts to make one in low-A. I do NOT recommend that key! I also make a Kokopeli flute out of PVC (similar concept) and found out that the finger spacing was pretty tough, too.
Also, on the “where to drill the holes” question. First, get your bell note (as mentioned above), and then just use Doug Tipple’s numbers.
Plunk 111- I just saw on a South American website that Acha - a quality quenacho maker cuts the top end at an angle so you don’t have to hold it horizontally. What size pvc tube did you use and what width , depth did you cut out the notch ? Am I right in assuming that you measure the distance to the holes from the bottom of the notch like the bottom of a low d whistle window, or do you have to compensate for the different window shape ?
bump
This is just a guy making quenacho out of metal and calling it a new and innovative instrument. I’ve been playing my self-made quenacho at sessions for quite a while, and I’ve heard of other folks doing it too. As for the thumb hole thing. I put them on my instruments, when I play Latin American music I use it, when I play ITM on the quenacho I tape up the back hole. In the case of quena(not so much quenacho), the thumb hole helps vent certain notes so you can get about 3 complete octaves. Here’s a set that I made to take to sessions. In the pile is a low B, C, and D quenacho, and then quena in E, F, G, A. Since the pic was taken I added a Bb, and Eb to my pile.
Nice looking instruments! I really like how you have bound each key with a different color.
I agree, if he was selling these I’d want one. 
I’ve made a low D and F copy of these open whistles and after a few weeks of fooling with them I can occasionally get them to sound though I’ll be dammed if I can figure out how I’m doing it. Using a lot of breath too. Can’t get anywhere near the second octave. I’ve read a lot about the Quena and Quenacho on the internet and the claim is the tone is real good once you figure out how to get them to sound so I’m not ready to give up — yet!
I made the notch in a PVC tube, I haven’t drilled the holes yet. but I can get 3 octaves. To get the higher octaves I just pinch my lips more to make the hole smaller.
On the most recent D before I drilled the holes I got a terrific bell note, after I drilled the holes I had no sound for a few days, then it started sounding again but not as good. Go figure!
It seems hard to get a clear and loud sound. I guess you must blow hard to do it ?