NOTE : You are going to be heating metal on your stove so please PLEASE take care!
You will need :
Jewellery settings - there are loads on Etsy, remember that you will be covering a similar shape with fabric so simple shapes will work best. The patina of your settings may change when you heat them so bear that in mind when thinking about the look of your jewellery - it may end up looking vintage whether you expected that or not! It's also advisable to avoid any settings that already contain soft soldered elements as these will most likely drop to bits when you heat them up!
Fabric - Choose a pattern that has elements in it that will nicely fit your settings.
A plastic milk carton with a flat area - this stuff is flexible, easy to cut and waterproof should your jewellery ever need a bit of a wash!
Double sided tape
A hot glue gun
Small sharp scissors
Pliers or tweezers
A gas stove
Start by cutting a flat section from your milk carton big enough to cut out templates from all of the settings you want to work with. Place a folded cloth that you don't mind getting singed on a flat surface with your milk carton piece on top. Holding a setting by its bale or loop with your pliers or tweezers, heat it gently in the flame of your stove - you want it hot enough to melt into your plastic but not burn it. Drop each hot setting face down on to your plastic and press it down with your pliers so that it melts into the plastic - sounds obvious but DON'T TOUCH IT!
Once your settings have all cooled down, remove each one from the plastic and trim the resulting shapes carefully with small scissors. I've used curved nail scissors on mine as they followed the curve of the hearts shapes really well. You may well find that some of your shapes have melted too much and shrunk away from the setting so they no longer fit, this means your setting was too hot - no worries though, it's a milk carton, just try again!
You will be coming back to the flame one more time but for now that's the dangerous part over! Take each one of your plastic shapes and cover it with a piece of double sided tape. Trim the tape to the edge of the shape and peel off the backing. Position your shape where you want it on the wrong side of your fabric, you should be able to see through the plastic to a certain extent to make it easier to get your placement just right.
Next, trim your fabric to shape with enough allowance to fold back around the edges of the plastic. Using your hot glue gun, fold the edges of your fabric around your plastic shape trying to get the edge on the right side as neat as you can. The wrong side is going to be inside your setting so can be as messy as you like!
Using your scissors or similar tool, ease the edges of your fabric-covered shape inside your setting. The 'cabochon' will now be more convex but possibly a little lumpy!
To smooth the appearance of your pendant and to ensure that the glue has properly adhered, gently reheat your setting over the stove once more, taking care to expose only the metal directly to the flame and not the fabric. You don't need it as hot this time - the glue will melt at a much lower temperature than the plastic did.
Once heated, drop your pendant fabric side down onto a flat surface and press down gently with a cloth to smooth the shape. A glass surface is great as not only is it flat but you can have a look at the fabric side to make sure you are happy with it, I've used a tea-light holder here.
Leave your pieces to cool for a moment, remove any excess glue with the tip of your scissors taking care
not to scratch your setting and enjoy making up your jewellery!