If sending us your stock to copy the inletting or duplicate the entire stock, please note these issues:
The stock will not come back to you in pristine perfect condition like you sent it. If copying only the inletting, there should be minimal or no marks to the outside of the stock, however there is the need to attach blocks of wood to the front and rear of the stock which then get attached to the duplicating machine. These blocks may be hot melt glued or epoxied on. When these are removed there is likely to be some small marks but the stock will still be useable. There will likely be some small marks to the top of the forearm where the flattening stylus rides along the stock. There may be some marks in the area of the trigger guard where that gets copied. There are likely to be some small marks from the inletting stylus on the inside of the inletting, but that doesn't really matter since it's on the inside.
If you are sending us a stock to have us copy the outside shape, there will be marks on the outside of the stock. If the stock is a soft wood like beech, plan on there being extensive marks from the stylus and from the flexure support fixtures. A walnut stock, being of harder wood, will not be so easily marred, but it is likely, in fact you should anticipate, that the stock's finish will come back scratched all over. Sanding it down and putting a fresh coat of oil on it will easily restore it's appearance, but I want to make it very clear that any stock that goes into the duplicator as a master will not come out looking like it went in.