Simple double hook designed to fit on the 7.5kg/15lb “3M Claw” picture hooks for drywall/plasterboard walls.
Do not assume that the hooks can support the weights assigned to the “Claws” but they seem very strong to me.
Easy print in PLA, the 3mf file includes a support blocker but delete it if you wish as the difference in quality is minimal.
It is a pretty tight fit but you could add some sort of adhesive, perhaps even BluTac, between the "Claw" and the hook if required.
Hope you find this useful, there is also a single hook version on Makers world.