I use little circles that my pencil goes through to mark seam allowances along curved seams, and a while back I created a tutorial for making these seam allowance guides by hand.
Recently I dropped the little box that I keep them in and lost the 1/4″ circle. It occurred to me that it would be easier to draw a new circle in Inkscape and print it out rather than drawing a new one manually.
So I thought, why not make a whole sheet of circles, so I can print new circles whenever I need to without having to redraw them? And if I’m going that far, why not make a metric set, too, and post them on my blog? So here they are: Imperial (inches) seam allowance guides and metric seam allowance guides. There are many sizes commonly used for seam allowances, plus larger sizes that you can use to draft facings.
To use these circles, print them out, preferably on heavy paper if you have some. If you have some full sheet adhesive labels, you could print onto those to make things easier. Make sure to print using the highest quality print settings and no scaling (100% or actual size). Measure the border to make sure it matches the dimensions printed in the upper right corner of the sheet.
These circles are not thick enough to work well on their own, even when printed on heavy paper. Roughly cut around a circle, then use double sided tape to stick it onto a piece of a thin, flexible plastic lid (like an HDPE margarine tub lid). Craft glue or rubber cement might work instead of double sided tape, if it will stick to the plastic.
If you don’t have an appropriate plastic lid to use, you can adhere the circles to a piece of paperboard, such as a piece of a cereal box, instead, but they won’t be quite as durable. If they wear out, you can easily make new ones, though! I used paperboard for the large sizes, since I didn’t have a plastic lid large enough. I also used clear box sealing tape over the circle to protect it, but that is optional.
After gluing or taping the circle onto plastic or paperboard, carefully cut out the circle. Use an awl or large needle to punch a hole in the center just large enough to fit your pencil lead through. Mechanical pencils work best, since the tip will always be the same size.
To use the seam allowance guides, stick your pencil lead through the hole in the middle, then run the edge of the circle along the stitching line. When you get to a corner or straight section, it helps to use the guide along the edge of a ruler.