This is a credit card sized holder for the Mace Picks sold by Sparrows:
https://www.sparrowslockpicks.com/product_p/mace.htm

The card is 0.85 mm thick, and should be printed in whatever layer height is suitable for your printer settings.

Once printed, I placed a piece of clear packing tape on the backside and then placed the picks into the card to be held in place by the tape. You could add another piece of tape on top after inserting the picks, but I found that it was not necessary and my wallet held the picks securely in place.