After all, I love all of the decoupaged plates and paperweights at John Derian (less so the prices).
My method is probably not classical, but I was quite happy with the end results!

I gathered supplies:
Glass flats from Behrenberg Glass Company
Decoupage medium–Mod Podge or Acrylic Medium, thinned with water
Something to apply the medium–sponge brush or brayer
Razor blade
Papers–I chose vintage postcards and personal travel memorabilia to suggest making a souvenir, but ideally you would use thinner paper (something the medium could penetrate)

Shops like Kate’s Paperie and Paper Source would also be great resources for beautiful papers.

Sources seem to vary when it comes to the question of to which surfaces you should apply the medium, but I found it easiest (and cleanest) to paint the thinned medium directly onto the back of the glass.

I had chosen an entrance ticket from our visit to Mehrangarh Fort in Jodhpur, and before I applied the medium, I had established which part of the image I wanted to use. So then, with the back of the glass painted, I pressed it against the image before spending some time working it from the center-out to remove any air pockets. You have to be careful not to tear the paper when burnishing it (especially if you’re working with something tissue-like).

After giving it a minute or two to set, I took my blade and trimmed around the edges of the glass.

You can clean up any rough edges (and remove any excess medium) by sliding the blade around the glass once the majority of the excess paper has been trimmed.

Here’s where a porous paper works best (though the postcards worked fine):  you want to seal the back by adding another layer of medium. Most then suggest painting the back with layers of varnish or paint, or finishing it with a layer of felt–though my lesson ended with a simple layer of the acrylic gloss. No doubt Derian does something really special to achieve such a seamless, glossy surface on his pieces and it would be worth trying different approaches to see what you like best.

Everyone’s paperweights turned out beautifully and my nerves were immediately calmed when I started chatting with all of the friendly and creative people who had gathered.
I’ll definitely be trying this again!

The feature ran on pages 60-63 of Rue Issue 3 this past January.
Here are some awesome outtakes from Trent Bailey, the photographer, and a few more posted by Anne on The City Sage.