The scaling factor is 4 for this design. For instance, if your smallest block is 3", it will fit one of the four inner squares of a 12" block, and the 12" block will fit into one of the four inner squares of a 48" block. For the on-point blocks, you first need to know the width of the bar pieces of the "underlying" blocks. But the scaling factor for the on-point blocks is also 4, so once you know the measurement for one on-point block you can easily determine the other sizes.

For example, in the 12" block, the bar piece width is 1-1/2". Twice that measurement is the length of one side of a right triangle, and the diagonal of that triangle will be (3")squared + (3")squared = (diagonal) squared. (Remember Pythagoras' theorem?) Take the square root of your result and you'll know the diagonal measurement, which is the size of your on-point block -- in this case 4.25". The next size on-point block will be (4 x 4.25"), or 17".

Here's a series of block sizes that will work to make this particular layout:

• Smallest Horizontal (Blue) = 3"
• Smallest On-Point (Fuchsia) = 4.25"
• Medium Horizontal (Red) = 12"
• Medium On-Point (Lime green) = 17"
• Large Horizontal (Purple) = 48"

Consider adjusting the outermost block to 44", simply by trimming 1" from the width of the long bar pieces (they will be 5" wide instead of 6", but the inner square will still be 12"). This puts the design in better proportion, but you will also have to remember to reduce the size of the Medium On-Point block to 14.25" as well.

Oh yes, as for the technical how-to's -- well, I haven't tried this yet! You'll be able to foundation piece the smaller sizes, but the outermost block would be more easily accomplished with standard piecing techniques. Incorporating the on-point blocks will also require some advance planning on your part and probably set-in seams. Good luck!