'Make' was a bit of an exaggeration: really all I did was cut and glued. Still. They were necklaces.
To make them, I just ordered some glass domes, premade bezels, glue, and ball chain off the interwebs. (You can find them at most online bead and jewellery type places, they are not expensive, and don't forget jump rings like yours sincerely.)
I found some images I thought would look nice, roughly cut them out, and then applied a good amount of glue to the back of the glass (I used Weldbond, and you do need something made specially for this kind of job, but most suppliers have their preference, so whatever they recommend should do just nicely).
The tricky bit is then applying one surface to another without air bubbles. It's harder than it looks. Either that, or I'm a thicky thick thick who can't glue things. I put a heap of glue on the glass, spread it out, and then just pressed it into the cut out design real hard until I couldn't see any air bubbles anymore. It meant I had a lot of glue pushed out to the side, but that was easy to trim off and clean up afterwards. And it helps if your paper is thick and strong, as the map of Paris was. The magazine paper I tried to use sucked the big one.
And there you go. They are teacher gifts for Christmas, and no, I am not super organised - though it's only mid November, my children finish school in two weeks. Two weeks people. God help me.