If you have a 3M Worktunes that uses a two piece headband that looks broken like this:

I made a one-piece FLEX design. Print with TPU. Printed 0.2mm STRUCTURAL, 2 perimeters, 10% infill, no supports. The slots have an overhang which retains the wires. The slots may need to be opened with a razor. 

I think the next iteration may have deeper slots but this works well enough.