Roman numerals

The numbers are made of 2-3 mm acrylic.

How to choose the right size of the numbers?
This question arises very often. There are no clear recommendations here, but you can follow the following rule: if you have a board with a diameter of 30 cm and you will install 4 numbers, then the size of the numbers should be 30 mm, if 12 numbers - the size is 25 mm, that is, one size smaller. If you have a board of 40 cm - then 40 mm and 35 mm, respectively.