How can I create a custom field that can be Viewable by a limited group like the Comment field?

Question

How can I create a custom field that can be "Viewable by" a limited group like the Comment field?  The Comment field is Viewable by all users, but can be restricted to be viewable by other subset groups.  I want to create another field with that option.

Joe Pitt · Accepted Answer

Can't out of the box. There may be a plug-in or you may be able to embed a script if you aren't on OnDemand