I make small flags for a motorcycle club. They are made from nylon that I embroider the club logo on. I sew a strip of fabric on each edge the same as you'd do on a quilt....binding.
You'd need to find "rip stop nylon" fabric to match the flags. JoAnn's sells rip stop nylon fabric & you can also find it on the internet.
I would overlock or serge the frayed edges first, then do the binding. Use polyester thread, as it holds up better for outside items. Do not use an iron, as it may melt the fabric. I finger press & use allot of pins.
You need a walking foot, or a machine that has dual feed, to sew it, as it is very slippery stuff to work with & also stretches in different directions. Use lots of pins or glue baste first.
I would also suggest when they get new flags that a binding is added, over the hem, before they are ever used. The flags aren't really made to withstand the wind on the back of a motorcycle, but by adding the binding first it will allow them to last longer.
The Patriot Guards also stand guard at funerals for soldiers or vets. An amazing group of people who give of themselves.