Apparently these plastic spools flip open and shut to dispense and protect the solder wick; just take out the wick and wrap your earbuds around the spool instead.

显然地，这些塑料线轴采用弹性开关来保护焊锡丝，把焊锡丝取出来，然后将你的耳机线缠进去。

youdao

The Shells are constructed out of ABS -- the same plastic used to create Lego -- which is fed into the printer from a spool.

ENGADGET: MakerBot's Turtle Shell Racers cruise around our offices (video)