The 6-ply diapers are more expensive, but I really like the thickness, especially down the center, for more absorbency. I could probably get the regular 3-ply, but they just seemed flimsier to me when I opened a package in the store. Many online reviews talked about these falling apart or not washing well, and people didn't seem to like them.
To make: pre-wash diapers and fabrics. Cut fabric the length of the diaper and as wide as you'd like. I made them just a tad wider than the extra thick strip down the center. On some of them, the edges wrap around to the back side about an inch and others it goes right up to the edge. For the quilted ones, I made five 5" x 5" four patches, and stitched them together into a strip (1/4" seam allowance). Press a hem on all sides of your strips and stitch on.