I’m wondering if there’s any way to make the hole of a torus smaller without changing the overall size. I could just scale in the inner ring but I’d like to change the cross section more evenly than that. Any kind of proportional editing I try does reduce the overall size. Of course I can do multiple scalings but am just wondering if there’s any simple technique. I’m using this for the iris of an eye, and might want to animate someday.
Yes there is a good technique for creating a controlable torus 
The method consists of creating two bezier circles. Use one of the circles as bevel object for the other one. By scaling the “cross section” curve you change the small radius of the torus. By changing the resolutions of both curves - you are changing the resolution of the resulting torus mesh.
A schematic example - below
Attachments
Thanks for that technique. By moving the cross section curve so that it’s ‘center’ was at an edge, scaling it had the desired effect of scaling in towards the center while leaving the outside radius untouched.
Well, it did the first time I tried it, but now I can’t get it to scale only inwards 
Don’t know what I’m doing differently.