Núm Chặn Đầu Dây (Rope End Knob)

This is a rope end knob to be used e.g. on the string of a scuba diving BCD/wing (the thingy marked on the image).

If you are printing underwater equipment, always use 100% infill and as many perimeters as possible. You probably want it neutrally buoyant and rigid.

On the thick side of the knob, simply make a double knot and pull the string/rope pack into the knob, so tthat the knot is securely stowed inside.

Of course you can also use the knob for all other kinds of string attached stuff.