Personal Pocket Holographic Projector

First introduced by Google under the name Giga, these devices were invented to replace smart phones. Although not as able to have as clear of an image in the projection, the affordability along with it's flexible functionality make it the "it" item of 2056. With a year Amazon and Apple start to compete as well.
By the end of the century the technology has improved to have 3D holographic projection as an option, albeit an expensive one. It had also completely replaced the smart phone as the projection technology has improved its graphical quality. Most every citizen has one with an ear bud attachment.

Utility

These devices are mostly used for communication and entertainment (games and video) although only on the go.

Manufacturing

Most are built in a factory with detailed focused factory robots construction and testing the product before it's shipped out.

Inventor(s)

Google

Access & Availability

Prolific, due to affordability.

Complexity

It's not impossible for anyone technologically savvy to build one, but one does need the proper training.

Discovery

Google began research in 2049, completed in 2056.