To get the floating shapes use a solid or near solid background fabric and contrasting colors for the inserted strips. I started with roughly 10" x 12" background blocks and 2 1/2" strips in variety of oranges to maroons. Then I cut the background block in half at an angle through the shorter portion and inserted a strip of fabric. So it will be roughly 12" x 12" once the insert is sewn in. The blocks will all be trimmed later.
Then I cut random sized strips through the block. I cut between 2" - 2 3/4". Layout an arrangement that you like. Then you will sew this strips together based on the layout.
Wait to trim the edges to square up the block until you have all of the blocks completed to determine your smallest block and then trim up based on that block.
Layout in rows that looks pleasing. Sew the rows together.
NOTES: There will be some small pieces cut off from the edges but save these for little projects. Also each row doesn't need to be the same size in width.