How to draft an octagon

To draft an octagon using just pencil, paper and scissors, no maths involved, you start with a square of paper – the required finished size of your octagon (plus ½ inch for a seam allowance, if you want to add it at this stage). You can make your octagon any size you fancy if it is not important – just acquire a suitable size of paper square. A large octagon (roughly 8 inches) can be made from an A4 sheet, a much larger one from A3 (roughly 12 inches), a smaller one from notepaper or a very small one from something like a Post-It. You do remember from Primary school how to make a square from a rectangle, don’t you?)

I’ve used A4 paper in the photos. Once you have a square, fold it half across one diagonal. Open out and fold in half across the other diagonal. Open out and fold in half down the middle. Open out and fold in half across the middle. You should now have a lot of creases in your paper, but as yet not enough!

Fold the square up along all those creases so you have a triangle. Now fold the long edge, with all the folds, to one of the shorter edges as shown. Crease again and open out the square.

Fold each corner of the square down, at the folds you just made, so the tip meets the diagonal fold. Crease.

If you turn it over you should have a perfect octagon. Cut the folded-down corners off and glue your paper octagon to card or plastic to make a sturdy template.

If your octagon does not include seam allowance then you can use the cut-off corners to make the square you need to tessellate with the octagon – the long side of the triangle is the size of the square without seam allowance.

To draw an octagon using ruler, compass and pencil.

Draw a square the size you wish your block/octagon to be. You can use your rotary cutting ruler for this if it is easier. Draw both diagonals across the square to find the centre.

Place the point of the compass on one corner and open out so the pencil is at the centre. Draw a line where the compass pencil crosses the sides of the square.

Repeat for all four corners. Join the dots to make an octagon.

Eight-Pointed Stars If you don’t cut off the corners from your folded square but add another crease you can just open it out to show all the creases which you can now use to draw the kaleidoscope block or 8-pointed stars and their variations. Or you can draw in all these lines onto your drawn square – just join the dots!

© Chris Franses, 2019