This is a prototype of a non contact, low temp, heating coil that's embedded in a cylinder. I made this by subtracting a "spring" helical shape from a cylinder and then subtracting a center rod from the cylinder. It was possbile to push a thin wire into the channel without any effort although I could have used oil to lubricate the wire. This can be used as a low voltage, low temp heating element that does not contact the central channel.