Accuracy in cutting out your shapes makes a big difference in the successful piecing of your block. One thing you may want to consider is purchasing acrylic templates. These are commercially made and they're a little bit heavier than something you can make yourself from template plastic. They come with a paper backing on it, which I've left on just so you could see it better on camera, but normally it would just be clear like your acrylic rulers, but they have about the same depth or thickness. What I like about using acrylic templates is you can often start by cutting a strip with your rotary cutter and then using them to sub cut. So whether it's using a diamond shape such as this to create your pieces, or using a specialty shape that allow you to cut multiples. This is designed to not only cut this sort of usual shape but also to be able to cut a hexagon. Now one of the things when I'm using acrylic tablets, I do like the precision and control-ability of using a smaller rotary cutter, so that's my preference. But with this there's a line at the top right where I can see where the top edge of my hexagon is going to be. And the bottom edge of the template lines up with the other edge of my strip. And all I do is simply trim around and cut away the pieces. I go all the way around the block. I'll have my shapes just like this. The other nice thing about acrylic templates is often the edges are trimmed so that you won't have big seam allowance dog ears. And those can help you considerably when you're putting diamonds together -- not to have that big wad of fabric at the center of your block. Give acrylic template a try if you haven't already. You might find that their accuracy is well worth the extra effort when you're cutting out.