Raziel The whole idea to design a belt without hinges sounds nearly impossible, unless you make it where it snaps together, making it impossible to remove afterwards.
Steel is bendy, especially in reasonably thin bands. Making such bands in the size of the wearer in question is a different challenge.
Taz The waist of a Mattel Barbie is 3.75 inches so about 1/10 of the average adult female.
Was surprised about that, especially considering Barbie's figure, but it works out realatively well. Volume does scale with the cube of linear dimensions after all.
Taz Too small for my current machinery but reasonably large by the standards of Swiss watchmaking. Maybe I can find a kinky watchmaker to help me one day.
I am not sure proportional scaling addresses all structural concerns, like rigidity, tolerances and lubrication. However, the square-cube law might be in your favor in some of those regards.