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This clip has an extra little bump on the top inner edge, to reduce the chance that it accidentally unclips itself.  It looks vaguely like a swan head.  It has been reshaped for more strength.  It would be silly to clip a 2.5 kg frying pan to your backpack (2.5 kg = 5.5 lb), but you could do it!

Print in PETG or some other filament that will flex without breaking.

Freecad file included for easy adjusting.  This is a modified version of the file that @Buggi included in the original, although it's not as simple to use.  In particular, I didn't consider making multiple sizes.  This clip is roughly 48mm x 28mm.  The diameters of the top and bottom loops are 18.5mm and 7.4mm, respectively.