These are Lilypad stitchmarkers for knitting (or Pac-Man according to my husband).
They should be able to fit up to a size 10US or 6.5mm knitting needle.
I printed my example in PLA matte, but should work just as well in PLA Basic or something else.
Mine is printed on a P1P, with 0.4mm nozzle, and a 0.2mm layer height.
Enjoy your knitting!