Have you ever wanted to have your very own at home theater but realized it was too much work and expensive? Well now you can make your own projector at home. This article shows how to make a projector with just a shoe box and a few other at home items.

Using LCD (light crystal display) and DLP (digital light processing) technology to display the magnified image, he cut off the lens of a magnifying glass and attaching it to the end of a shoe box. After cutting different parts of the box to tailor to the lens, he created a stand for the phone to rest on. Then he put the top of the box back on and turned off the lights, turning the projector towards a blank wall.

http://www.instructables.com/id/Build-A-Smartphone-Projector/

This relates to engineering because the projector incorporates LCD and DLP technology to portray the digital images. A color wheel shines light through a lens which enlarges the image. Mechanical engineers create projectors and similar technology.