The Disappearing 4-Patch or 4 to 9-Patch starts with a 4-patch block with good contrast in colors or shades and tones. The one below was made with 5 inch squares and it will finish to a 8.5 inch block from raw edge to raw edge if accurate scant 1/4 inch seams are used.
Next, make 4 cuts without moving the block or the cut pieces. Use a small mat so you can turn the block without disturbing it. Using the center seams as the reference point, measure out 1 inch and make a cut; then make a cut on the other side of the seam. Rotate and repeat, measuring 1 inch from the center seam for each cut.
Next, rotate only the center outside sections 180 degrees as shown in the photo below.
Sew the sections together as shown in the next two photos to complete the block.
There you have your new 9-patch block. You can vary the look by the width of the cut. This block makes a great charity quilt because it is fast to sew and looks complicated.
This block can be done starting with a 9-patch but using a 4-patch allows one more freedom to get the look desired by varying the width of the measurement from the center seam.