69 Cougar Full rolling Chassis

Good day fellow Cougar lovers. Has anybody built their own rolling chassis? I’ve searched hundreds of sites for a full chassis. Yes there are many companies who build them but not cheap. If you actually look at the material involved its quite simple considering its only boxed tubing. Cant cost that much. Yet these companies charge a fortune. Money I’m not ready to part with. I am a welder by trade. Cant be that hard??? Or can it. Anyone know of where I can purchase a set of blue prints to build my own??