The JonRocket.com Fin Guide Tool generates a custom, printable template for aligning fins along a body tube. The template can be glued to a piece of craft foam or cardboard and cut out to make a jig for helping to align the fins and hold them in place as the glue dries.

Paper Size: Select Letter, Legal, A3, A4, or A5 based on the size of the paper in your printer.

Body Tube: Select the body tube that you are using or "Other" to manually enter the diameter.

Body Tube Diameter: If you selected "Other" for the Body Tube, then enter the diameter of the body tube. Be sure to select the proper units in the "Units" field.

Body Tube Units: Select the units for the manually entered body tube diameter ("inches," "millimeters," or "centimeters").

Fin Count: Enter the number of fins.

Fin Thickness: Enter the thickness of each fin.

Fin Thickness Units: Select the units for the fin thickness.

Fin Span: Enter the width of single fin (from the root edge to the outer edge). (Note, this differs from the usual definition of "fin span." See the diagram below.)

Fin Span Units: Select the units for the fin span.

After you click the Submit button, the template will be downloaded as a PDF file. When printing the template, make sure to select the "Actual Size" setting. The outer square in the lower right should be one-inch wide and one-inch high. The inner square should be 20mm high and 20mm wide.