How do I go about making a knife sheathe pattern for a knife I don't have?

[mrCung]

Hello, I am figuring out some if the logistics of starting a small business.  My plan as of now is to sell discounted leather sheathes because I am a novice. My only concern is making a sheath pattern without having the actual knife on hand. What would you do then? Would I have to have the customer ship out their knife to get a proper sheath made? 

Thanks a lot for all of your input!

[DieselTech]

It is best to have the knife. Or a well replicated model of the knife to make a well fitted sheath.