Inquiry regarding HS Code for printed packaging and entry on Purchase Confirmation

We are a company that manufactures and supplies packaging materials, and we are currently preparing a Purchase Confirmation as we are exporting masks to the United States. I have a few questions: 1) When printing on Polyethylene Terephthalate Film (HS Code 3920.62-0000) to be used as mask packaging, which HS Code should be applied to the printing process, and how should the HS Code be entered on the Purchase Confirmation to qualify for the zero tax rate? 2) We have newly manufactured printing cylinders (for gravure printing) required for this printing process; I would like to know the HS Code for these cylinders. 3) What kind of disadvantages or penalties might occur if the HS Code is entered incorrectly?