Hi Stephanie,
I have a co-worker that buys unused bottlecaps and glues images (about 1 inch ones) either inside or on the outside then drills a hole in the crimped side and adds a jump ring to it. She paints some of them before adding the image. Then she puts a clear coating on them and threads ribbon through the jump ring.
She also glues them to the flat back of clear flat-backed marbles and glues on a bail then threads ribbon through the bail. She did say that sometimes there are cracks or bubbles in the marbles that distort the image. I've seen plastic flat backed marbles on the internet somewhere. But, that may not work for you since it's stickers - unless you put them on paper first.
Just some thoughts off the top of my head....
Cathy
"What matters in life is not great deeds, but great love." - St. Therese of the Child Jesus
"The laughter of a child is the light of a house" - unknown