hi Fitz
well there is no issue i tell you why if you like cape off coffee is because you like the look ,shape ,wight and feel ,100mm or 101mm is ok
you dont take the tape masure and musure it
tolerance off the externall size + or - 1 mm is not an issue to the finish product
ex: gaz tank externall size 500 or 501 is ok is going to fit in the bike yes
manufacture the organic shape or molds is done with cnc 3 and 5 axes is not an issue