“I can’t believe we are doing this,” Grey Henson says, his voice nervous, his eyes thrilled. “I can’t believe I’m on camera right now.” Henson has come to the Playbill Studio to showcase his newly honed makeup skills. Only, he’s not delicately applying brown freckles or carefully flicking each brown eyebrow hair. No, he’s enthusiastically applying thick strokes of brown contour to his browbone to c…