Zend certified PHP/Magento developer

Product Attribute Multi select

I am trying to replicate this kind of attribute (categories) in a custom attribute. There is a way to do it?
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I means, the text input field with the search bar with the multi select option to assign to a product.

I see another kind of attribute (Add to option in a Configurable Product with a pop up modal) that will be used but maybe it could be harder to do it.
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And then the modal
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