I would take it to an auto upholstery shop or a shop that makes boat covers. I'm assuming you want a canvas,cloth or vinyl type material. I have one that was on my 60 C10 when I bought it, that's made out of a convertible type cloth material that snaps on.
It does look nice when installed, but I usually leave it off.
Joe

54 Triumph TR2(rhd)needs total resto.
60 Apache 10 stepside shortbed
99 Excelsior Henderson