The C10 Conversion Ruler is a remarkable help for positioning the centers of a 10-Combination Division (Jyuttoubu no Kumiawase) in Temari making. While the paper-strip approach for dividing and marking divisions is the gold standard in Temari making, a few modern tools have emerged to help with the 10-Combination division; the V-Ruler has been the most common one in use but is being phased out of the Japanese curricula and the JTA in favor of this helpful kitchen appliance. Guidelines for use can be discovered on TemariKai.com https://www.temarikai.com/HowToPages/C10RulerAi.html as a quickly printable page.
These conversion rulers have actually been created and produced in Japan by a JTA Kyoujyu/ Shibu-cho. They are printed on flexible yet resilient product and can be found in two parts: the C10 Conversion scale in addition to a millimeter strip so that you can inspect positionings with ease. They might be used individually or, more commonly, peeled off the self-stick backing and adhered together to form one reversible tool. This ruler is scaled for use on mari as much as 80cm in circumference (see Little size for use on smaller mari).
No more having to determine or offer around a reference chart for C10 centers versus circumference … all that is had to understand to utilize this is the circumference in cm of the mari.