I still have concerns about the repeatability of camera positioning, especially if you have to manually reposition each time. An indexed position with a physical reference and hard stop is much more reliable. If you're doing an engrave that isn't re-doable, such as on an iphone, and if you're doing more than one at any regular interval, you want something extremely reliable. I have in the past build index tables to accommodate things like iphones, I would suggest doing the same with glowforge. Additionally, you can use the PDF documents to cut test blanks to test your index table and make sure everything lines up. Maybe the camera positioning will have some repeatability functionality, but just in case I'll have a backup plan in place.