That is so cool your son wants to sew. Good for him!!! Tell him not to cut into the seams...close, by not into them or they'll unravel. I also do 1/2" but I haven't done big blocks. I think rectangles would look really great. Unusual for a rag quilt. My first rag quilt was jeans, and I didn't know much about sewing so I only used 2 ply thickness. It worked. My niece uses it in Texas where it's really hot. I bought a pair of scissors that are spring loaded to cut all the edges. Helps so much. I think if he makes kind of big blocks, he won't get burned out on it.