Hi Michael,
I believe we're on the same page. Though persistent relationships would be great (like that afforded by a constraint middle-ware engine like D-Cubed); that's not what I was asking about or hoping for now.

Indeed at this point the suggestion, or if you will request, is that whatever object you're editing it would be possible to establish a relationship, albeit temporarily, using the very same variables that originally allowed defining that object. For instance, in the box example you'd be able to make the length equal twice the height (x=2*Z). Or similarly for a cylinder, relating radius or diameter and height.

Cheers,

- Diego -