I’m surprised at how many people make their own whistles. How in the world does one find out the do’s and don’ts on this? Are there special tools you need? 
there are several websites out there that tell how to make whistles. http://www.geocities.com/dwisely/bloodyhand.htm is the only one I can think of at the moment, though
You can buy a great TW for 50 cents or you can ruin a perfectly innocent piece of brass or copper pipe and use up a couple of hours for 3 bucks…
Naw I prefer to waste me time working on flutes.
:0)
Might I suggest starting out by learning to tweak cheap whistles…