Created a slim/minimalist flipping wallet for 6 cards. I highly recommend inserting 6 cards if you use it (cards will hold in place even if you turn the wallet around).

What you need:
4xM2 12mm (i use machine screws but normal screws will work too)

Instruction:
If your printer has soluble support material, do not follow the instructions above and just print horizontally.
Otherwise:
-Print left and right parts vertically (brim highly recommended)
-Remove the supports where the links will be
-Print 2 "links"
-Tricky parts: You will have to remove the support inside the screw column (Yes, the hole from the bottom and top screw is the same, thats why the lenght of the screw you will use does not matter). To remove the support, fit the m2 screw inside the holes and screw until you see the support's plastic coming out from the opposite side of the column. So if you are pushing in the bottom screw you will see plastic coming out of the top hole.
-Screw the 2 links so that the wallet can flip

Printed on a Anet A8
30mm/s speed
0.2mm height
0.4mm width

Highly recommand a brim (10mm+) even tho I have been able to print them only using a skirt. (Failed multiple times as it would fall on the last layers)

Make sure that it only does a support for 85 degrees+, otherwise it will create a support for the center circle.

I would really be happy to see somebody make it with a good printer! (Mine has many issues)

I have been using this wallet for my 6 cards for the last 3 months