usually your batting squares are 1" smaller than the outsides, so if making 9" squares your batting is 8" placed in the center and(quilted)... lots of people just stitch an X across each square to keep the batting from shifting. then an easier way to get the clipping done is, as you join each row of blocks go ahead and clip the joining seams (which will not have anything more added to them) then the next row and keep going then as i join each row i clip the in-between seam...so by the time it's all together i only have to clip around the outside. it is easier that way than to sit and try to cut the whole thing at once. i love raggy quilts with flannel and warm&natural...and i've experimented alot. a couple i even cut my batt the same size and let it (show) in the fringe. it turned out ok...definitly fuller in the clipped edge...but was very noticable, so if i were going to do that again i think i would dye the batting to match. but it works so well with the smaller batt squares...
anyway, once you start making them, everyone's gonna want one! they are so soft/fluffy and great to snuggle up with!