Cable ties are great for creating a custom sized loop. Whether it be for hanging or attaching objects.
Step 1: Melt to Lock
Once the loop is adjusted to the correct size. Simply cut the excess leaving 5mm excess tail protruding.
Get a lighter and melt the excess tail until it bonds with the locking end. Stub out the flame using a flat screwdriver.
You now have a custom size locked cable tie, which will not retract any further.