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Keychain to insert micro SD and SD cards, it has internal holes to insert 6mm x 2mm magnets,

(The magnets are inside the piece, you have to insert a pause in the laminator and place the magnets. Think about how to place the magnets so that when you close north and south they are in the correct position)

be careful with the polarity and think very carefully about the placement to insert the magnets so that later when assembling the keychain they attract each other and the keychain closes well

You will need:

M3 screws and nuts, the length will depend on how many layers you are going to put on your keychain) with 3 inner layers your keychain will have a total length of 19mm.
then the thread length (L) of your screw should be approximately 16mm, the head of the screw (k) should in no case be more than 3mm. The magnitude of (d1),(e) and (s) of nuts are the standard measurement M3,

a circular screw head is required like this: