There's copper tape, and maybe some metal tapes in a silver color, but will leave that to others who know better.
any suggestions for finishing techniques that don't require a blowtorch?
As for finishing the edges of polymer pendants though, there are a bunch of things you could do, even if the piece is already cured, and many of them could simulate real metal:
...apply a metallic color only to the thin outer side with:
........Krylon leafing pen
........Rub 'N Buff or another metallic wax
........mica or metal powder (in a clear carrier since they won't stick by themselves now that the clay is baked... something like Varathane, Future, clear acrylic fingernail polish, acrylic gel medium, or even thinned permanent white glue)
....apply a clay rope of some type only around the outer edge of the piece (to help hold the raw clay to the baked clay, you may need to use a bit of liquid clay, Diluent-Softener, clear acrylic or even white glue in-between them ...or just let them sit together overnight before baking)
........the rope could be a different shape, or you could impress or texture it before baking to give more visual complexity
........... could even use a metallic powder or paint on the clay frame (textured or not) --completely covering it, or just hitting the highest areas ("highlighting")... or use metallic leaf (crackled or not)
....apply clay rope/etc. just on top of
outer edge (possibly with your piece on a background... then trim them even (see Donna Kato's lesson, for one)
...."stack" your piece on top of a flat shape of clay that's wider and taller than your intital pendant (using a plain or patterned clay) to create a faux frame ... can cut it out from the polymer sheet with a cookie or other cutter, or with a long blade, or the tip of an Xacto knife, etc.
(Or do some combination of those.)
If you want more info on any of those techniques and materials, check out at least these pages at my polymer clay "encyclopedia":http://www.glassattic.com/polymer/frames-mirrors.htm
(...click especially on Very Small Frames
(... click especially on Framed Pendants
+ Stacked Pendants
ALSO maybe:http://www.glassattic.com/polymer/texturing.htmhttp://www.glassattic.com/polymer/powders_metallicwaxes.htmhttp://www.glassattic.com/polymer/paints.htm http://www.glassattic.com/polymer/leaf.htm http://www.glassattic.com/polymer/Faux--many.htm
(... click on Metal, Silver-Pewter, Gold, Copper, etc