I found two plastic cards (like a CVS or Safeway club card) and put double-sided tape on the front side of each card.I then inserted the cards simultaneously— I inserted a card tape-side up at the very bottom of the disc opening, and I inserted the second card tape-side down at the very top of the disc opening. After inserting the cards about 2 inches into the disc opening, I caught the mini-disc right between the cards.
Big Hint: Use thin plastic cards, like the rewards cards you get at Safeway, Walgreens, CVS, etc. They're a lot les flimsy than paper business cards.