Something like that, absolutely would work...

My thoughts however were more along the lines of something suitable for a microservo, to keep it as light and compact as possible.
A bit like a plugvalve. Since you can print 3D, square holes (linear area increase) in the plug and body should not be an issue to print, no?
Although I an not sure if linearity really is that important, given the free programmability of the curve.

But what I am thinking is, it might be a bit more "size limited" (a smaller engine requiring a narrower valve passage than a larger engine).

I have to say, I absolutely like this...