After learning about June Tailor rulers in this thread and getting the link to her videos I watched every one of them.
I've always had trouble getting half and quarter square triangles right and I was impressed with her ruler used to make these pieces.
I found one at Walmart on Friday for $11.99 and I was thrilled. This morning I made 16 perfect half square triangle blocks without having to rip any out.
You can bet I'll be stocking up on June Tailor rulers when I come across them at a reasonable price!