The question is not whether modern investigators can figure out some way to produce a reasonable copy of the Shroud but, given the quality of forged Medieval artifacts in general, why they would have produced a forgery so good that modern researchers still puzzle over it and that’s so difficult to see without modern photographic equipment. We’re talking about people who painted Biblical scenes with all sorts of ahistorical details and were fairly careless with other forged artifacts (for example, the spear that supposedly ws the Spear of Longinus in Vienna dates to the 7th Century) producing a hard to see image in normal light that accurately reflects not only a real crucifixion but also contains details that conflict with what was commonly depicted during that period and accurate details of a Jewish burial.
My conclusion is that if the Shroud of Turin turns out to be a fake (and I don’t believe it is), that it’s either a copy of an authentic original or, far more unlikly in my opinion, it was produced by a Medieval artist with researched Judaism extensively and crucified (murdered) a person (or more than one person) to get the details correct.
My opinion it is if this Shroud is not the Holy Mandylion looted by the Crusaders from Constantinople then it is a copy of the Greek church's Holy Mandylion from Constantinople. The making of high quality reproductions of relics was not seen as a forgery and copy of a relic was seen as worthy of veneration and highly sought after in the west.The west may have had primitive technology but Constantinople was far from primitive in artistic skills and technology.