Here are three projects that I recently completed.
This one is made with 14 colors. Make a chain half as long as you want the width to be. Decrease by 2 stitches at the same end of each row until you finish the pie wedge. Start the next color and run it the length of the first wedge. Decrease each row as before. I joined with single crochet. You can also simply sew the two sides together. Then go around the afghan with each of the colors used in the wedges. (Done in sc, ch stitches)
This round one is simpler than the one above. Simply increase each row by 12 stitches. I ended up with visible "corners" because it was easy to increase in the same place on each row. (Done in dc)
And one mile-a-minute pattern.
We have - or can get from another library - patterns similar to this for anyone who's interested.