Cuts half square triangles from 1/2" to 6" (finished size) in one step
Using the Easy Angle
Before cutting strips, fold your fabric once parallel to the selvedge edges, with selvedge edges together. Then fold again in the same direction. Trim along one side of the folded fabric perpendicular to the selvedge edge to square it up.
Determine the finished height of your triangles or the finished side of your triangle square (two half-square triangles sewn together to form a square) and add 1/2" to get the needed width of your strips (which will then include 1/4" seam allowances. Use an acrylic ruler to cut strips this wide. To cut triangles so that they are ready to sew together to make squares, place two strips right sides together and cut them at the same time. The fabric from each of the strips will make up one triangle in the square
Trim the end of the strip(s) to square them up.
Line up the bottom of the tool along the edge of the strip(s) and slide it along the strip(s) until the end of the strip(s) fill the triangle area shown for the required size. The number corresponding to the strip width should be in the upper corner of the strip (2-1/2" here).
If you have two strips laying right sides together, each time you cut you will get two triangles ready to sew to make squares. After sewing, press them open. After cutting, flip the tool over its long side (the hypotenuse), line up the edge of the strip(s) with that edge, and the black triangle top of the tool below the strip as shown. Cut along the edge perpendicular to the strip. Continue with these two cutting steps for additional triangles.
To cut squares (and rectangles), cut strips as wide as the unfinished square (rectangle) width. Then line up the edge of the tool with the top of the squared off strip as shown and slide the tool along the strip until the end of the strip lines up with the square (rectangle) length. Cut perpendicular to the strip.
These steps are the same for easy angle 6-1/2" and 10-1/2".