An octagon is an eight-sided geometric shape. Each of the eight sides is of equal length on a regular octagon, but can be of unequal lengths on an irregular octagon. These line-segments join together to make a closed form with eight corners. A recognizable example of a regular octagon is a stop sign, located at the corner of most intersections. A regular octagon can be made larger or smaller by increasing or decreasing the length of the sides, and it can be cut from any material needed for a project.
Create a square of the correct size for your project. Draw the square onto the back of your material with a straight-edge ruler. Make sure the sides are of equal length and that opposite sides are parallel to one another. Using your angle ruler, check to make sure each corner is 90 degrees.
Draw a line from each of the opposite corners so the result is an "X" intersecting at the center of your square, dividing it into four equal triangles.
Find the exact center of each side of the square with your straight-edge ruler. Mark lightly with your pencil. Bisect your square again by connecting these marks across the center from side to side. The shape drawn this time will be a "+" that divides your square into four smaller squares.
Measure the length of one segment of your "+." Begin the measurement at the intersecting midpoint of the square and end at the point that bisects the side of your square. Record the measurement.
Create new points on each of the arms of the "X" that are equal in length to the recorded segment. Begin at the intersecting midpoint of the square and mark the endpoint of the guide measurement with your pencil.
Connect the end of each new point on the "X" with the end of each "+" segment where it bisects the side. Erase the extra facets outside the newly connected segments of your shape to reveal the octagon.
Cut the octagon from your project material using the appropriate tool.
You may be able to find a premade octagonal template to use as a cutting guide.
Create a reusable pattern using this procedure on a piece of template paper or plastic.