Several people have asked me how I cut the perfect little circles — it is thanks to Maru-kiri (丸きり), circle cutting knives! They are originally made for Katazome (型染), the Japanese traditional stencil dyeing method.
I purchased them from Osugi (大杉), a manufacturer of Ise Katagami (伊勢型紙, the traditional stencil paper) in Suzuka city, Japan. They also manufacture and sell all the tools and materials you need for this stencil crafts, including Maru-kiri.
The diameter of Maru-kiri are all in mm, and there are 31 different sizes:
Still, if you cannot read Japanese it might be difficult to place an order on their website. I found Maiwa in Canada had some Maru-kiri in their store
https://maiwa.com/collections/japanese-technique which are currently sold out, but maybe you can back-order…
This beautiful thing in their store seems similar to what Maru-kiri does:
Tools for handcraft are art and artisanal products themselves!