A 0.2 nozzle is recommended but not required; The hole the post goes through is 1mm in size.
Several styles are available to accommodate your straight-post earrings:
When you're done printing, simply snip between the ball and stopper; They are ever so slightly fused together to ensure a tight fit once they've been opened.
PLA will work - but might be uncomfortable for little children after extended wear.
PETG will work better, since the “grab” wont be as strong due to PETG's flexibility compared to PLA.
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