Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:1826436.

Front of center measuring tool to calculate the FOC of an arrow

FOC %=[(L/2)-P) *100/L

FOC %=[(total lenght of the arrow/2)-Point of balance from the top) *100/total lenght of the arrow

FOC = [(30 inch / 2 ) -13] *100 / 30 inch = 6,66 %

V1: another Version :) V3: fits for feathers with 4 or 5" V4: Optical improvement