To make the yoyos for my Yo Yo Pomander (Yo Yo ball ornament) I used adhesive vinyl (also known as Mactac, Contact Paper, adhesive vinyl shelf paper, Fablon or sticky-back plastic) to make my circle template for cutting and basting. (The finished yoyo will be a little bigger than half the diameter of the circle. eg. A four inch circle will make a yoyo a little bigger than two inches.)
I find 24 pleats works well for most fabrics so I marked this template with 12 spokes each cross the center point. This is easiest to do with a protractor. (360 degrees divided by 24 = 15 degrees.) Then I marked the halfway point between each spoke with a red slash. (See 2014 update below for an easier way to create templates.)
To use the template I stick it to the right side of the fabric,
and cut around the template, leaving a generous 1/4 inch between my scissors and the template.
I fold under one section of fabric that corresponds to one spoke so that a little less than an 1/8 of an inch of fabric shows beyond the the template.
Then I am ready to sew. I bring my needle and thread up at a line and down at a red slash, checking that the needle has gone through both layers of fabric. I continue folding and stitching ...
until I am back at the beginning.
I remove the template and stick it to my next piece of fabric. (If I'm not planning to cut another yoyo I stick it to a ziplock bag.) Now I can gather and finish the yoyo.
I can use one adhesive vinyl template over and over but when it does start to lose it's stick I will stick it to a new piece of adhesive vinyl and cut around it. Then I still have the template with the lines on top and lots of stick on the bottom.
If I want to make a yoyo without turning under the edge I cut the fabric a little less than 1/4 inch outside the template. Then I sew the running stitch through the single layer of fabric.
I just found a web page online that one could use to generate templates of various sizes and number of pleats. The generator is for Kumihimo Bracelets but it would work well for yoyo templates too. To use this generator one would enter the number of lines needed to make the spokes in the "number of strings" box. So, for example, if I wanted to make a template with 24 pleats I would choose "12 strings". Also note that the diameter of the wheel only comes is even centimeter increments but if one creates and prints a a wheel that is slightly larger than required one can easily draw the spokes and then cut the circle to the desired size.
Click on the photo below to visit the generator. (Today on Chrome I'm getting just a half circle but on Internet Explorer I'm getting the full circle.)
Pinwheel 2009 and 2014