Keeping in mind the variety on offer, we've listed lightweight portable projectors with built-in batteries that work well with your smartphone and are priced under $500 at the time of writing.

Those projects fizzled out, most likely due to the cost of the projectors, but we got a few laughs out of it: that wearable smartphone that projected a screen onto your wrist used the same technology.

An curved arrow pointing right. It's really simple to build a projector for your smartphone to be able to project the same types of holograms seen in Star Wars and other movies. Here's how!