Virtual reality headset
The headset is the viewer and your phone is the screen. Slide an Android phone or iPhone into the cradle behind the front cover, and the lenses split the picture across a 120° field of view so it stops being a rectangle in front of you and becomes the room around you. Adjustable head and crown straps plus a padded face rest carry the weight, which is what lets you sit through a full feature instead of taking it off twenty minutes in.