You will need 10 6x3mm neodymium magnets per complete slider, 5 per each half.

Print x2 slider flat on the print bed. Tested in PLA.

Different print bed surfaces yield a different feel. Such as more or less magnetic feel. I find very smooth print surfaces require the least break in time and have the strongest magnetic hold together. More textured print surfaces allow more slip between the parts.

You will have to pause the print to insert the magnets into the model while printing. Pay attention to the orientation of the magnets. One slider piece will be “north” and the other “south”.

Personally when I am inserting magnets, I arrange them into a tall stack, after completing one slider half, I flip the entire stack over and do the other slider half.