The bobbin is made of two parts that glues together, the bobbin cover needs to drill a hole according to the used wire diameter (or additionally ad in slicer) to thread through the wire.

Glue the bobbin pieces together, drill the hole to the cover, wind the wire, thread the wire end through the cover, snap the bobbin into the cover and enjoy!

Print preferably in PETG, layer doesn't matter so much. If needed can be scaled (scale in all axis).