I always use Fons and Porter tool where you put the point of the tool at the corner, and draw your line on either side to the other corner, stitch those two sides on the line and cut down the middle. That is usually a 3-7/8" square and when it is cut, it is a 3-1/2" square . When the instructions have it at 3-1/2, I draw my line down the middle and end up wasting 1/2 the 1/2 square. I just follow the directions, but I still love making the 1/2 square triangles! Edie

I, too, use the add 7/8" or 1", and diagonal line. I give a quick press over the seam but DO NOT press open. I cut the block to size while still folded by putting the corner of a ruler toward the point, and aligning precisely the 3-1/2 mark on the right side and left side and then cut. Thus, not having to cut twice (two sides, turning and cutting two sides). Then carefully press the seam to the side.

Yes, you will have "the ears" which you can lop off after pressing. I find that if I roll my hand rather push the rotary cutter, the block not will be distorted.

I was taught that if you want the finished size 3 1/2" then you need to add 7/8' to the finished size in order draw a line and sew on each side of it. Your square would have to be cut 4 3/8" to start

I vote for cutting it 4 1/2 inches and cutting it down to the 3 1/2 inch size. Better safe than sorry.

If you've ever tried to rip out a .2 stitch, you know it's not going anywhere, so go ahead and use that to lock your stitches!

Question 1: I like to cut my squares bigger and trim down. That way don't have to worry about a scant quarter inch seam. Instead of cutting 4 3/8" I'd cut 4 1/2"