I've used small diameter PVC pipe for spacers, people have cut up plastic coat hangers as spacers, and currently I am using "mini popsicle sticks" available at craft stores as spacers. I've used regular 12awg insulated stranded wire as a conductor and am currently I'm using some "lamp cord" that I pulled apart as my conductor. I don't expect it to hold up in the weather but for now it is working. I use "Goop" industrial adhesive to fasten the spacers once I get them in place. You'll have to stretch out both conductors and apply the same amount of tension to both when you are placing your spacers. If you have one wire more taut than the other, your spacers will not be straight. I just drilled holes in my popsicle sticks with my drill press and slid them on, but you can obviously cut a slit and slide your spacers on. If you are going to use PVC, plastic coathangers or some other material for your spacers and you don't have a bandsaw, it can get really tedious cutting the spacers one by one with a hacksaw. That's what led me to use the popsicle sticks and so far, to my amazement, they've held up in the weather.