I like bracelets, and have made several bangles in all polymer as well as bangles and cuffs using brass channel blanks. One of the problems with a closed bangle is sizing, since peoples' wrists vary widely.
These last three bracelets were made on a different bracelet form, one with 2 thin brass bands. These bracelets are very easy to put on and take off, but I wanted to be sure they wouldn't come off too easily during wearing. I found a magnet and clasp combo that works just perfectly in the opening on these bands, and makes a nice "safety" chain. The polymer flowers and leaves are on both sides of the brass bands, securing the design to the base.
I think these bases work perfectly with polymer, and I'm pleased to have found bases that support 3-dimensional work.