Originally Posted by
nativetexan
If you must have a line, you can use a Hera marker which only makes an indention, not a mark. sew on indented "line".
I do this also but first I put one pin and pin the square to the corner it will be attached to. I started drawing a line on the squares but felt it was stretching the fabric and like you, I didn't want to draw all those lines first. I pin, draw with the hera marker then sew one thread or so closer to the outside corner across the square. That works the best.
I came up with an "assembly line" way as I had hundreds to do. I pined and marked four blocks(all I had room for near me). Then sewed, trimmed, flipped and "ironed" with the Hera marker. I was able to work my through all those squares without going crazy.