Plus even though the CNC step is the big one, there is a good week of work in electronics and in the plastic parts, each.
So finally got the details cut into the pistol grip. On the surface, simple enough; create a spline, turn it into a pipe and use that as a tool to make a boolean cut. Except not, of course. I haven't found any shrink-wrap or surface following in Fusion3D yet -- only the ability to snap a point to an existing point or plane (which half the time ends up adding the point to the previous sketch or body or whatever.)
And the way that operations are supposed to stack in history...meaning you could edit the spline curve to correct the look of the cut...well, that didn't work. So I had to do the cuts by trial and error. And that was after sort of figuring out how the spline tools work (apparently there are at least two different edit modes. In one, constraints show up as icons that can be deleted. In the other, constraints do not display and the only way you can figure out if they are there is by toggling them on then toggling them off again. For every single selectable point.
The other mild success is I hooked up the 2.5 watt mono amp to the surface transducer, and taped it down to a nice solid chunk of machinery (a nautical clock I happen to own). And it was pleasingly loud, especially when I hit some natural resonances. Probably not loud enough to be impressive at a convention, but with luck this will work for the prop. I'm starting to get concerned about interior space, though. The transducer takes up a big chunk of space and there's not a large hole between where the trigger mechanism has to go and where the potentiometer is mounted for the knob.
Oh, yes. I also ordered pot, trigger switch, a rotary switch in case I change my mind...and the metal. Hopefully the CAD won't suddenly call for stock dimensions larger than I estimated.