Find a collage that you like (or make one!)
I searched for "cat collage" on google and choose this one, but there are hundreds.
You can choose other things too, like eyes or fruits, get creative!

You can jump this step if you are making your collage the messy way :)
Now it gets a bit tricky!
Go to your photoshop program (or paint, in my case haha)and edit/cut/copy your image until you have a "necklace shaped" thing. Print it, then encase it in the contact paper and cut it.

Make holes on the upper "tips" of your print and attach the chain and the clasp.
You can put the clasp on the middle on the chain too, but i was too lazy to do it :P

Now be proud of yourself and post your version!