Just a few days ago I watched a short video of two color Continuous Prairie Points on favequilts.com. No special ruler was needed, just a regular quilters ruler. If you google continuous Prairie Ponts, there are several on You Tube and there are many variations to choose from. I have bought several rulers since I started quilting, but only one specialty ruler, the Fons and Porter Half and Quarter Ruler that I thought I absolutely needed, lol. I have two rectangular rulers , a 3" X 18" and a 6" x 24", a 12 1/2" square up, and a set of fussy cuts. Have not used any but the rectangular for any of the blocks that I have made and the square up. Most can be done without specialty rulers, but that is only my opinion. I guess, for me at least, I can buy more fabric if I spend less on items like rulers that I really don't need.
The scallops are a bit of a different story; my GF, back in our highschool days showed me how she did a scalloped hem on a skirt by simply drawing half way around a cup set between two parallel lines drawn on the wrong side of the material about 6" from the hemline. With right sides together, sew on the curved lines and trim away the excess from the folded edge. When you flip right sides out and press, it made a great scalloped edge. We learned that if there's a will there's a way and to learn to improvise. Again, no need for a specialty ruler.