Google Nexus 4: permanent back panel glass repair for less than a penny

Clear packing tape. Apply single layer everywhere on back panel there isn't a device port. Be creative.

Has worked for me for months to prevent further damage.

Cost less than $ 0.01.

Doesn't look "pro" but neither do $20 - $30 covers from Toys-R-Us and other similar stores.

I actually only covered the area below the camera and to the left of the speak/microphone/whatever with one single piece I had to cut a bit to size.