Summary

This spool will fit the entire length of the KEEMIKA USB Endoscope, if you wind it on there neat and tidy..

Assembly method would depend on the filament you use.
I used PETG, and welded the parts together. Added some filament with a 3D pen, then melted the joint together with a soldering iron.

Then the spool will fit in the camera's original box. Put the little accessory capsule in the center hole.

If printer software imports an impossibly tiny STL file, try the "Metric" versions. They are scaled 25.4 times larger.