My scrap bins are about 10" x 15" and 9" deep. The purple one was nearly full. It still has 4-5" left at the bottom and the rest went into these 12.5" slab blocks. Sashing is 3" and I've made a bunch of 5.5" ones to use in the border. It will finish 73" x 88" so is a good size.
I am amazed at how far the scraps go, and how relaxing it is to sew them like this. Not a lot of planning, just sort to sizes and think log cabin but not too accurate. The sashing is a red-purple fabric that will go between all rows, around the outside, and likely be the binding too. So far so good.
Oh after taking this picture it is easier to see the values, so I moved a few of the blocks around. Purples do not like the camera either. I'm not much of a purple lover so am surprised at how many scraps were in that bin!