A few days ago I got a few of my students together to create a smartphone projector. I'd seen a video of it online and it seemed pretty easy so I'd ordered the parts required and over the course of a lunchtime we created our projectors. The process was cheap and simple. To make the shoebox projector all we needed were:
A smart phone
The most difficult aspect of the whole process was the cutting out the circular shape for the magnifying glass as the shoe boxes were quite thick. However it was worth the effort as the results were excellent. It required a bit of tweaking to get the image clear but overall the result was well worth the 45 or so minutes it took to create a final piece. I'd recommend you use a very strong magnifying glass as this will dictate the quality of the image. If you have a spare hour or so why not try it yourself?