Pardon my asstastic photography- these were done around midnight the night I finished them, bad lighting in the apartment, no one around to take the shots, etc., etc. But you get how it works, especially how long the back piece is supposed to be.
Instructions on how to make it:
(a) Buy six skeins of Cascade 220 yarn (or just get a lot of worsted weight yarn of your own preference, doesn't matter). I used three colors. Gauge is seven stitches across and six stitches high = 1 square inch.
(b) This pattern is knit flat, but I ended up having to use size 8 circular needles in order to make it wide enough- it didn't fit on my straights.
(c) To start either side, cast on 168 stitches in Color A. Knit for 2 inches in garter stitch, then switch to color B. Knit color B in stockinette stitch for 2 inches. Then switch to color C and knit 2 inches in garter stitch. Then switch to color A and knit 2 inches in stockinette.
(d) If you are knitting the back piece (which should be about 8 inches long- stops around the back where a chair back might go), stop at this point and bind off.
(e) If you are knitting the front piece, continue the pattern as set, alternating garter and stockinette rows, until you have six 2-inch rows of each color completed. It should optimally end slightly below the end of the person's waist. Bind off.
(f) Pin together the two pieces for 10 inches at the start of each long side, leaving a large hole for the neck. Sew the sides of the poncho together, creating a blocky shape.
Feel free to alter this around if you like, making more sloping shoulders, changing the stitches, using more or less colors, making it less wide (I was making it for a man's shoulders), whatever you need to do.