Those are so beautiful, I absolutely love your work. I use washi tape as well. I place them inside pendant bezel trays and then use Mod Podge to glue glass cabochons on top for a very similar effect. You have given me inspiration to try wooden blanks and polymer clay. I mainly work in glass. Washi tapes are so versatile.
Check this video ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-6MN7KtV4QJc.html and about some wood shapes here ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-IrZYkrIgn2s.html