One name for a gimmicky item is 'gizmo', which is used to describe something very useful for a particular purpose, or a device whose name is unknown or forgotten. It frequently refers to a small item.
A term for an unusual article is 'curio', which literally means a curiosity, something odd, different or unusual; it can especially refer to something worth collecting.
You might also call such an item a 'gimmick'which - among other definitions - means an innovative or unusual device.
A 'gadget' also fits your description, with the same meaning as 'gimmick', above.
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