Step into the lobby of downtown’s Alexander hotel (333 S. Delaware St.; 317-624-8200), and you’ll find the lady herself, Madam C.J. Walker, staring at you from an oversized portrait. At first glance, the work looks as though it was made using a giant dot matrix printer. But upon closer examination, people discover that Sonya Clark created it using plastic combs — 3,840 of them.