I am left-brained in construction, so I did have to have some boundaries.
I chose the block and colors through random selection. You can read more about that on my BLOG.
This is my finished project. It measures 17.5" x 18.5". On my blog, I mentioned how this was a learning experience for me. It could have been truly MORE improv if I had made the outer border randome blue and orange, or if the log cabin strips had been placed without consideration of the rule: 2 sides dark, 2 sides light.
I will try something like this again. Perhaps I will use some other block choice from my list.