Abstract: A method for making a lead body for use in a conductive insulated lead for a cardiac stimulator. Alternating layers of conductive and insulative thermosetting polymers are extruded through successively arranged heated nozzles of increasing outlet diameter. As the inner layer emerges from its nozzle in a thermoset state, it is passed through a following nozzle while surrounded by another thermosetting polymer that is extruded through that following nozzle. The second polymer becomes thermoset and bonded to the already thermoset inner layer. Successive nozzles can be provided to form successive layers of alternating conductive and insulative polymers, where the conductive layers serve as the electrical conductors of the lead.