I used a part of watches for this pendant as a base ;)
You need the following materials and tools:

• watch glass
• copper wire 1.1 mm
• copper wire 0.3 mm
• alcohol (to degrease)
• stained glass paints and glass contour
• decorations
• wire cutters
• pliers
• a small hammer with an anvil to slightly flatten the wire

The first part can be implemented with children :) Degrease the inner surface of the glass and paint waves on it:

Then make such detail out of wire and a bead:

When the contour is completely dry, paint the surface between the waves with stained-glass paint:

And join the details:

And, voila! The pendant is ready, just add a lace or a ribbon:

Thank you for your attention!