So just a small, but cool little calculated field that may come in handy for our custom greenfield card makers...
The card that xanatos linked includes the relevant shipment ID, but for some reason includes an apostrophe at the beginning. This means that even if you display it as a barcode it won't be recognizable by your myDevice.
Insert the following card calculated field:
dimension(pad_left(right(trim(SHIP_I), 17), 17, s'0'))
Basically, if the field, "SHIP_I" is more than 17 characters long, it displays only the right most 17 characters, which removes the apostrophe. I don't know if this was the best way to achieve my desired goal, but it worked!
I attribute this knowledge to greenfielddocsites.target.com, and the fact that you can look at the card calculated fields of other users on greenfield