Is a Mask enough?

From my Crimlaw class:
Professor R: “Is a buying a mask enough to be in the possession of a materials to be employed specifically designed for an unlawful use?”
Jill: : “No. Maybe it’s Halloween or something.”
Professor R: “Well, that’s right. You can use a mask for a lot of things. I just to have a colleague that taught Criminal Procedure in a Nixon mask…”