I'm writing up a few details for the Sew Modern Bee block exchange, May is my month. I decided on Confetti blocks, most of the confetti blocks I found on flickr had the solid as the background. I am working with the prints as the background. All of the prints are Kaffe Fassett and the solid is Kiwi from Timeless Treasures. 
I cut print strips different widths, from 1" - 2.5", and the solid into smaller segments for ease of use. Everyone will receive a variety of print strips and a 4" solid, plus a strip of solid to use as confetti pieces. You don't need much of the solid for each block. The blocks are 10.5", I have been working with much larger blocks lately, I wanted to work with something more manageable, and I think 10.5" will give me a nice size quilt that I won't feel overwhelmed about the quilting.
I chose a few print strips to work with for one block and a solid center. I am using the word 'center' loosely, I don't necessarily want the solid in the center of the blocks. On both sample blocks my 4" square is off center, and in one block I cut the solid center in half. So if you think it will look good, do it! 
I added print strip pieces log cabin style, but DO NOT make a traditional log cabin! I want the strips to be different sizes and prints mixed together. An example of how to add strips.
I sewed pieces of the solid into the strips to get the confetti splashes of color. And just because a strip is 2.5" doesn't mean you have to leave it that way, if you want it to be 1", cut it down. But I do want the pieces to all stay squares or rectangles, no wonky cuts, please. These blocks and then the whole quilt will be linear and have straight lines. 
As I was playing around getting my samples together, I cut this center 4" solid in half and added a strip print. This is how I would add strips to the foundation I was currently working on. Don't think too much, if it looks good, add it! 
It is easiest to make the block larger than 10.5" and then cut down. If you want to leave your blocks slightly larger and I will cut down, I can do that. Without having to worry about being exactly on the 10.5" mark, it takes away any math stress. And anyone who knows me, I am a bookkeeper, I run a business, and I suck at quilt math. 