So I found this image floating around online and printed it out on a sticker paper. With trial and error, I found out that the optimal size for this is 35.56mm x 26.67mm (1.4in x 1.05in).
https://docs.google.com/document/u/0/d/10ll6xE_Yes1LxdC1wgIjoxvUVrNxu6oxhZuTcPcaewU/mobilebasic
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