Here are a few options/ideas:
You could use
beading chain or thin cable chain. All the types of chain in that link, should be thin enough to string multiple strands through a large-hole bead. If you click into the details of those products, they have links to the crimp tube components to finish the ends with. You would also need a
clasp, plus a jump ring for the other end.
There are a lot of necklace design ideas, plus explanations of how to make each design, in our
Design Gallery.
WireLace is kind of cool, and might work for multiple strands -- you can use the Search function in the design gallery to see how some of our designers have used it.
Magnetic cable chokers are popular for fused glass pieces, and for lampwork glass beads, because they're inexpensive, durable and easy to use. However, they would be single-strand chokers.
Depending on your type of fused glass pendant, you might need a bail. See the third row of our bails page for
Aanraku drop bails, tube-top bails, and other gluable bails and pendant plates.
Here is wide variety of cording for general jewelry purposes -- be sure to check out the
Rattail satin-like cord -- it's a lot prettier than its name would lead you to believe!! And it works well for multistrand necklaces. Click into the details for usage hints.
Do any of those sound like what you're looking for?