Complex sentence: The Costin chassis was never put under a production car, instead the early Roadsters featured a TIG welded stainless steel tubing frame, and extensive use of CNC machined and stamped parts.
Split into simpler sentences: The Costin chassis was never put under a production car. All the early Roadsters featured a TIG welded stainless steel tubing frame, and extensive use of CNC machined and stamped parts.