I believe the hexis for mine are 2 3/4 but I'm not sure. I got all of them cut out and now just have to keep sewing them all together.
But I measured how wide a hexi would be side to side and point to point then cut strips out with those widths for whichever would get me the hexis out of a piece of fabric. then I cut them into rectangles and later cut the points off if that makes any sense at all. But you probably don't have to cut the points off. Good luck!! and we'll want to see pictures as you get them done!