I was very fortunate to win a give away recently from the Quilting Gallery at the 'not so basic quilting tools' post.
These stencils allow you to mark your fabric to construct half square triangles. I'd seen them in blogland but didn't know where to get them. Now I can tell everyone you can get your own at Sunday Best Quiltworks.
I rough cut two squares from complementary contrasting fabrics. I followed the directions on the stencil label and there is also a video on you-tube.
I prepped my fabric by using a little spray starch and ironing the pieces right sides together. I pinned the stencil on and used a chalk pencil to mark the sewing line and a lead pencil to mark the cutting line (I used different colours to help reduce confusion - I need that).
After sewing, I chopped them up as directed, pressed to the dark side and trimmed the ears.
The hst's were pretty accurate, except I did discover that the white fabric was a poly or poly/cotton blend and didn't behave well (it had been given to me as I usually try to buy good cotton fabrics for quilting).
I give the stencils an A+ rating and consider them a valuable addition to my quilting tools.