AFAIK, the only working chastity belt for women that was not made of stainless steel was the Reinholds from Germany. Their belts were made to measure out of glass/carbon fibre reinforced epoxy. Sadly, Reinholds has gone out of business.
Until someone else steps up, the only way to go for a female belt (for more than just playtime) is custom made stainless steel, for reasons of comfort and hygiene.
The plastic belts currently available are just "plastic".
As with the male CD's, metal is the way to go. Looks better, feels better, is much easier to keep clean.
But be prepared to spend from US$ 400 up. But if you want her to look like that ...
Manufacturers of female belts are
Carrara Designs in Belgium (Walter Geothals):
http://www.carrara-designs.be/
Walter comes to the US every year, so you could have one fitted there
I do have a bunch of .wmv files that show Walter doing business in the US, very informative
Tollyboy (UK):
http://www.tollyboy.com/
Wiliam Jones (US):
http://www.williamjoneschastity.com/
Mysteel (Germany):
http://www.my-steel.de/
Neosteel (Germany):
http://www.neosteel.de/ (US):
http://www.neosteel.us
HTH,
K