Which yarn material for encasing LED lights, if any?

This feels like something I should be able to easily Google but Google is becoming surprisingly unhelpful.

If I were to create a project that encased LED lights to make a cute hanging, such as leaves in a bunting format, which yarn material is best? My gut says cotton because it can be used as hot pads etc, but I am also aware that it's flammable.

If anyone has made such a project, what did you use? Are LED lights even the most appropriate lighting?

Than you!