First, bend down the edges of the bottlecaps with a pair of strong pliers. You may be able to do without this step, but it helped me a lot!

Remove the plastic bits inside the bottlecaps. This can be easy or hard, depending on the type of bottlecap. I had two lots of them, one type which wouldn't come out no matter what, and another type which came out easily if pulled out with a craft knife or thin knife.

Flatten the bottlecaps! It's easiest to do this if you put it between two blocks of wood and hit them with a hammer. You can flip the bottlecaps over and move the wood around until they're as flat as you want them

Drill the holes! I can't tell you what kind of drill I used as I don't have a clue, but you'll know if it's small enough to go through but big enough to fit a jump ring through. You'll need to hold the bottlecap in the pliers again, over a block of wood and drill straight down through the rim

(I don't have a picture of me doing it with the bottlecaps, so just imagine that simcard is a bottlecap haha)

I found that the inside of a bottlecap is exactly 1", so you can either resize a picture on your computer using Photoshop, or look through magazines for an image the right size.

Cut it out using a craft knife or a pair of scissors

Use a strong glue to glue it onto the inside of the bottlecap, then go over it with a gloss varnish to keep it hard

Almost done! Now what you need to do on each earring is slip a 6mm jump ring through the hole and do it up again. Then open a 5mm jump ring to put through the 6mm one, and put an earring hook on that too.

Close the jump ring and you're done!