Lauren,
I have made art magnets for many years. I go to Office Depot and buy the 2" X
3 1/2" precut magnets. Then my students and I crop their drawings, painting,
digital art, or whatever to this size using Photoshop.
I print out an entire page of each image and cut them with a paper cutter. I
glue them to the magnets using spray adhesive. To make them "shiny", I apply a
strip of packing tape to the top and trim them.
I know this is not a fancy, smancy way of doing it, but it works for me and
my kids.
Here is an example of what I am talking about: