I have made some modifications to my original hollow doughnut tutorial which I think makes the process easier (and the back of the pendant flatter).
*Edit: I’ve also done a video demonstration for making a hollow pendant.*
Prepare a sheet of polymer clay with a surface design of your choice e.g. mokume gane etc. It should be fairly thick (2mm for a 5cm diameter doughnut).
Cut out a circle using a cutter slightly larger than you want your finished doughnut.
Place your cut out circle face down on the BLUNT side of a slightly smaller cutter (this will give it a nice dome). This will be the finished size of you pendant. Make sure the edges of the clay circle are still above the top of the cutter’s edge.
Prepare a sheet of coordinating clay for the back. This should also be quite thick e.g. 2mm (same as the clay for the front). I have textured mine using rough sandpaper.
Place your backing clay face down on a surface you can bake (I have used a tile). Place it down carefully to avoid air bubbles. Prick the clay with a needle tool (this helps keep the back flat).
Place your domed front clay onto the backing clay. DO NOT apply pressure at this point – it should just rest lightly in place.
Use a small cutter to cut out the doughnut hole. As the dome is only lightly resting on the backing clay it should allow excess air to escape while you press down the inner cuter for the hole.
Now press down the outer cutter to get a good join with the backing. I use my roller to press down as the sharp side of the cutter is up.
*There is a picture missing here*
Remove both cutters. Manipulate the edges of your dome so the edges slope gently to the backing. I use my fingers or a knitting needle. Now use the sharp side of the outer cutter you just removed to cut off the excess backing clay.
Make sure there is a good join all around the doughnut including the inside of the hole. I use a knitting needle to smooth the edges.
Bake your clay according to the manufacturer’s instructions. If you want a smooth pendant sand at this point.
Depending on how well your backing clay blends with the front you may feel your pendant is finished at this point. However I often like to apply a contrasting edging.
Roll out clay to the thinnest setting on your pasta machine and cut out strips (approx 5mm wide).
Apply a strip around the inner hole and smooth the edges using a knitting needle.
To even the top of the edging I hold my tissue blade parallel to the base of the doughnut and cut around.
Remove the excess edging. I use a needle tool or the back of my scalpel blade to do this. Bake again and your pendant is finished.
And the back of the finished pendant is pretty flat.