Product type: https://www.zazzle.com/pd/spp/pt-odt_paperpad?style=12x18
If I make a border of consistent width on this product type, it looks correct in the design tool, but in the Zazzle auto-generated mockups, the border is no longer a consistent width, it is thicker on the right and bottom sides.
I tried putting a photo of a face in that border area on the right, and the face looked stretched in the mockup. This confirms that whatever we add to the design tool is getting stretched in that area of the mockup.
Design tool Auto-generated mockup


