It's Sew Easy!
HSTs are one of the most common units used to make quilt blocks or even whole quilts - like the one I'm currently pattern testing for Crafty Little Mouse.
I'm making the throw size (you guessed it, as a rainbow!) which has around 65 HSTs to make, so I though it an ideal opportunity to put the new Patchwork Triangle Ruler by Sew Easy through it's paces.
My initial observations before use were that it's sturdy and seems well made, it has been laser cut which allows for precision cutting as your rotary cutter runs smoothly along its edges, the measurements and markings are clear and easy to read - I really like that they are in red as it shows up well on fabrics and my black cutting mat.
I especially like the fact that it has a straight edge/cropped tip on one of the corners so you can get rid of the dog ears on HSTs easily.
For accurate squaring up of HSTs make sure the 45 degree line is placed exactly on the centre line (stitched seam) and that edge of the ruler is on the finished size you need for your HST - if you look on the right hand side of the below image you'll see it's on 5.5" which is the finished size I needed. Simply trim the excess fabric off either side, flip the unit over and trim the remaining sides in the same way.
As well as trimming you can also use this ruler for cutting accurate triangles to the exact size needed, far more useful than trying to cut a square in half if that's your thing.
It's also a great compact size so will easily fit in a sewing bag or case, another great feature if you do a lot of workshops or social sewing.