Wow, your blocks look awesome!
You can also do paper/foundation piecing without sewing thru the paper, that is the way I prefer.
I also like to use inexpensive muslin (think Joanns .99yd with additional 50% off) to use for foundation string quilts, OR some ugly fabric that I have with no desire to make a quilt out of it, I turn it to the lighter, wrong side and use it so the color/pattern won't show thru to the side that has light fabrics on top. I hate ripping off the paper, so I prefer fabric foundations.
warm quilt hugs, sue in CA