The light angle helps, no doubt, but the depth of the ink in this microscope photo of a one dollar bill is impressive. Keep in mind that the dollar bill is only 0.0043 inches thick (o.1 millimeters):
If buying new kit is currently a little outside your budget, why not just learn how to fold a miniature camera using a dollar bill? It might not satisfy your photographic urges in the same way, but at least it will take your mind off being broke.
That single that's been wadded up in your front pocket for the last two weeks? You're just a way station, my friend. Because it's seen and done more than you could ever imagine. Here's its secret history.