The SIS units are very basic, so using traditional techniques works well for them. The diamond unit is more difficult. You could use Tri-Recs or the Deb Tucker ruler for that one. I bought a special ruler set and loved the way mine turned out. It is the Wendy Mathson Trimplates. You get the accuracy of PP but you don't have to tear off the paper. A lot of people don't like to buy specialty rulers, but in this case the accuracy is worth the price to me.
Darren