I would continue producing by building buffers of simple layouts which you will find readily available when the order comes. That will eventually save you time and get the customer's order ready in no time. If you want to discuss further let me know so i will explain more in detail.

Depends where you are from. Check your nearest industrial areas where you can propose to them that you are seeing that you will be buying an X amount of boxes per year and see if they are willing to do a sample just for you to check.