This is a variation of Adam L's “StrongArm: A Table & Desk holder (hook) for bags and purses and headphones”.

I had printed some of his version for friends of mine and they found the hooks were constantly sliding off the tables when they tried to use them. In order to fix this, I created a TPU pad to provide some grip, and modified the hook so that the TPU pad can slot in without requiring any sort of adhesive.

Unlike Adam L's version, mine does require supports.

To place the TPU into the hook…
1. Insert one of the long edges into the slot (honeycomb pattern facing out).

2. Gently bend the TPU until the other long edge fits into the slot.