The original "harness" was adapted from a suitcase strap. It was a long, synthetic strap designed to be tightened around an over-stuffed suitcase to keep it from breaking open when abused by baggage handlers. The same strap could be passed around the shooter's back and around his shins directly under the knees. It was tightened by a sliding, synthetic buckle allowing the shooter to more easily acquire and maintain the over-arm or off -the-knee FT position.
Fwiw, the first person I can recall using a "strap" was Robert Frtederick, but many others adoped it around the same time.
This was back in the early "90s when rules were deliberately flexible to encourage innovation in a relatively new sport. The "strap" was allowed in the Open class and evol;ved into today's harness. The BOG under the leadership of the Kirkendoll brothers, Gerry Thomas, Rodney Boyce, Roz Sumpter, Brad Troyer, the Shmizus', and other early members intentionally minimized rule making to allow our sport to grow naturally. AAFTA was intentionally designed to be unincorporated so as not to be affiliated with the laws or rules of any jurisdiction or group of people - especially the NRA. It was intended to accomodate all people and - remarkably - still does so.
Folks interested could try a "strap" to get a feel for it. There are no design criteria, so creativity may result in a superior product. Yea!