I made an all green one, hand pieced, cutting 2-1/2" wof strips into 2-1/2" squares as I went along. I started at the center with a single square of the darkest green, then put squares of the next green on each of the 4 sides of the beginning square to make a '+' shape. For the next round, I attached the 3rd green at one of the points, then 'stair-stepped' the 8 squares of this round around the center '+' to create a diamond shape. I continued in this manner with each additional round until it was the overall width from point to point that I wanted. My biggest round had 19 squares on each side of the diamond (a total of 39 squares across). At this point I started decreasing the # of squares on each side to create the 4 corners. The final 'round' consisted of a single darkest green square in each corner.
I am now at the point of deciding whether I want to add a border or just sandwich and bind 'as is'.
This is not a particularly quick way to do it, but very easy to take with you wherever you may be, and does not require a lot of concentration while you are doing it, so lends itself very well to doing while visiting with family and friends or while watching tv.