1st example with the use of TULAS.

The flexible loop connection is made with a few cm's of TPU filament.

For more info on TULAS, how to connect the filament and how to use it with your own models: 

TULAS: the universal hanging/strapping system

Note: As a TPU filament I tested with Ninjatek Ninjaflex which has a hardness of 85A. If you use TPU with a higher hardness (e.g. 95A) you cannot pull such tight knots and the chambers for the knots are too small. So use TPU of 85 Shore or lower.