I did a slight modification. My badge needs to always be seen at work, so I have it hanging from my keychain. With this card holder, I was able to fit my badge, driver's license, and two debit cards, so I now no longer have to carry a wallet at all. Also, as long as I have my car key, I know I haven't forgotten my wallet. Excellent design. All four cards fit just fine with no bending. Printed with PLA.
Edit: Tested sliding cards out with my keychain addition. First two cards slide out very easily, so I just keep my debit cards in the back where it's more difficult for them to slide out. For the record, there is no reason for me to believe ANY of these cards will slide out on their own. They are in there shockingly securely.
Edit #2: Although, if only one card is in this card holder, it rattles and slides around. Not recommended for use with a single card. ( Might just be my fault or the cheap printer's fault.)
Modified original file: Added hole for keychain.