I was pleasantly surprised that a light touch of my thumb released just one card at a time. The spring seems to work. It holds 1 - 10 cards. It only took one design iteration to get the spring to work correctly.
I know, I should have put the “Greetings” facing the other way. If 3-4 of you ask me to revise it, let me know and I will do so. And tell me where it should be located, i.e., where it is now, or near the open end.
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The author marked this model as their own original creation.