I use fine copper wire...sourced from various electrical cords, ranging from speaker wire, old guitar cables and wiring harnesses from the old runway/taxiway lighting at my airport.
I wrap a length around a needle...
As you wrap, you can slide the wire, to get a tight coil. Once you're done, slide to coil off the needle. If you pull the ends just a little, you've got a spring (think auto springs), keep pulling and you've got your coiled cable...