This luggage tag accepts a standard 3.5" x 2" business card as the address label. I tried to print a few of the address labels that have an address raised or recessed, but they weren't very readable. I had printed a beer tap handle with a slide in buisness card sized label and wasn't able to find something similar, so I remixed the beer tap handle into an address tag!
I added a second tag that isn't quite so large that uses a custom size card insert of 2 3/4" x 1 3/8". I also made the hole smaller to be attached with a zip tie or different smaller type of tie. This size looks much nicer on backpacks and small carry-ons.
Depending on your printer and filament, it may be helpful to slightly trim the business card so it slides in easier. I have a 2" tool that I use to remove prints that I can slide right into the slot for the card to break away any little areas that would block the card from sliding in. With a slight card trim and cleaning the card track out with the tool, business cards slide right in.
I did try to print this in TPU, but because of the overhang it just didn't work very well.