A useful pack of three identical credit-card-sized trays that each hold four SD cards, giving storage for twelve cards in total.
The trays are completely open at the front and back, and require some sort of back panel or a clear card wallet (or some sticky tape!) for stand-alone use. A strip of duct tape seems to work well.
For production handling, the three panels are threaded by a small loop of "non-contact" sprue which will normally need to be twisted off or cut away to separate them before use. The sprue isn't actually attached to any of the panels.