I read it on one of the email lists.. either ample knitters or maybe Big Girls Knit list - I think it was Ample knitters actually..
In fact here's the quote:
<Just passing on an idea gleaned ala Lily Chin from an appearance on
<KnittyGritty. She marked lines on a piece of elastic one inch apart.
<Stretch the elastic over your garment with the appropriate number of
<markings between your top and bottom edge. Mark your garment <and go for
<the gold. I have not tried it but as it was demonstrated I had an aha
<moment - no calculations involved.
Fun idea, I saw it in Lily's class also. They reason I use simple
calculations, instead, is that (A) I know for certain the holes will be exactly the same
of rows apart. With the elastic you have to have the front laid out with
absolutely no "give" in any spot, otherwise it won't be accurate. (B) I always
knit both fronts at the same time. When I knit my calculated buttonhole, I
place a 6" piece of dental floss into the matching center stitch on the other
front. Using that marker, I know exactly where to sew the button and have it on
the exact same row.
Another buttonhole hint is to use your swatch and place a buttonhole in it.
Two reasons....you can see what the selected hole will look like in your
yarn/stitch pattern.....and you can put it in your purse when you go hunting for
the proper button. You can slip it into your swatch hole and make certain
it's the right size.