I make crazy and strip quilts with fabric as the foundation. I've never actually tried with paper - this is how my gran showed me so that's just what I do. I have used old sheets as Gran taught but the quilts get SO heavy, so now I keep my eyes open for super thin muslin, or even really cheap-quality quilting cottons if they're on sale and lightly colored. I do pre-wash my foundation fabric. I rip my foundation into squares around 13-14 inches and then cut down to 12-1/2 when I'm done. I draw the 12-1/2 square on the fabric before I start (a quick trace a template with blue water-erase pen) so I know about where my "true" edges are going to end up, and like one person mentioned I try to avoid bulky seams near the corners and edges.
I love these types of quilts. They're fuss-free, a great way to eat up scraps, and I like how free and creative I can be while piecing them.
