[Source] Piano wire coiled into a spring

I am looking for a supplier of piano wire that is coiled into a
spring. The wire needs to be approx 28 gauge–coiled into a spring
that is approx 61/2- 7" long with an outside diameter of 1.5-2mm.
One end of this spring must be narrowed so that it fits inside the
other end (and can be lasered together). The purpose of this is to
be the ‘inside’ of a bracelet that has no closure, but stretches to
get over the hand.

hello Barbe, A steel guitar string makes great coil spring wire. You
can just form hooks on the ends of the coil and assemble it that way
instead of lasering. This will make it easier to service in the
future. Have fun.

Tom Arnold

A steel guitar string makes great coil spring wire. You can just
form hooks on the ends of the coil and assemble it that way instead
of lasering. This will make it easier to service in the future.
Have fun. 

I used to make springs for my catches out of my old guitar strings
as well. Problem was, they rust kaput and that was a major mission.
Now I use stainless steel spring wire.

Works very well.
Cheers, Hans

There are any number of spring manufacturers who could make your
spring, but I’d hazard to guess that, unless you’re purchasing a
very large quantity, it would be prohibitively expensive. Googling
"spring manufacturer" or “coil spring manufacturer” will bring up
many results.

Mike DeBurgh, GJG
Henderson, NV