Ronaldo makes a good point (as did Tommy), frequently assumed by some of us old codgers. Work safe! And acetal gives off peroxide too, so the same caution applies. Besides, if you can smell PVC/CPVC while you are turning it, something in your procedure needs to be adjusted.
Feadoggie
Feadoggie,
Thanks for the comments and the pictures - beautiful work there. I did the search re the pinned plugs as you suggested. From that and your pictures it appears the reason for the pins is aesthetic. Or have I missed something?
For now I’ll just go with the glued CPVC plug and worry about looks later. Bronze pins on the tan CPVC would look pretty decent now that I think about it - maybe some grey Delrin.
Thanks again.
RVC
The pins on my whistles started out as a construction choice, and once there, I made them a cosmetic point of interest, sort of a trademark really. The glowing miniature LED in each head is really cool. 
Or so some have said. I use different colors for different keys. I investigated several types of glue and a few strategies on how to set the the adhesive between the three parts. I was never satisfied with gluing. Pinning is clean, it works on delrin and I can punch out the pin to disassemble the head if that ever becomes necessary.
But “spacey glues” work - “a little dab’l do ya”. Just don’t try polyurethane glues or any of the so called hydrophilic glues. You’ll wonder where your windway went. 
And yes, bronze or brass pins look nice on tan CPVC or black delrin or brown delrin or…
Feadoggie
I originally started out making heads from Delrin…but Delrin is much more costly to learn on than CPVC. CPVC pipe is readily available in the 1/2" trade size, and although it still must be bored out, it’s a big time saver. I continue to use the Delrin plug simply because it gives a nice contrast and has a nice feel, but I also find that these two materials fit well together - it is easy to get a good tight fit between them.
The biggest reason I pin the head is to keep everything where I want it. Everyone eventually drops a whistle… But pinning isn’t necessary per se - it’s just the carpenter in me demands it as a matter of principal
I used to do quite a bit of plumbing work (new homes, etc.) and used PVC for drains. PVC cement is nasty stuff. It isn’t actually a glue. PVC is joined by the process of a solvent weld - PVC cement actually dissolves the plastic a little so that the two parts being joined are “welded” once the solvent carrier evaporates (the cleaner actually softens the plastic even more, for a better join). Although CPVC is approved for water lines, I don’t think putting anything with PVC cement on it in your mouth is a good idea - even when dry. The level of exposure to it that one would get from water passing over it in a pipe is very different from actually touching it to your lips or skin. Many glues continue to emit chemicals (formaldehyde, cyanide, etc.) long after they are “dry”. Many products containing glues that are considered “safe” are classified as such simply because the normal level of exposure to these lingering chemical emissions is low.
I tried glueing, I should say solvent weld with one of my early cpvc designs. 1st it didn’t work and 2nd it is hard to keep the glue where you want it and not have it dissolve the tube somewhere else! After careful machining you get to apply a ‘glue’ which somewhat randomly softens the plastic - think about what you have to do to make a good water pipe joint.