For squaring up half square triangle blocks, you can't beat Eleanor Burns Quilt in a Day "triangle square up ruler.' they are squares that come in 6 1/2 and 9 1/2 inch sizes. They will do increments up to the max size, so you get a lot of bang for your buck. After you sew the blocks, before you open them, you line up the correct size on your stitching line and trim the excess. Then open and press. I have both sizes and they are among my must-have tools.