Decide what size you want your blocks to be. Mine are 6 1/2" unfinished. When they're sewn together, they'll be 6 inches. If you prefer, you could make your blocks larger or smaller.
Using your "chunks," cut a few squares in different sizes -- any size you like. For my blocks, I cut them anywhere from 1 1/2 inches to 4 inches. You can even cut them in 1/8-inch increments.
Select a "string" you'd like to use for your first row. I don't use strings that are less than 3/4" wide at any point. This ensures that I have enough width for at least 1/2" that will be used by the seam allowances, leaving me with 1/4" for the strip that actually shows in the block.
Place your string on top of the square. Using scissors or a rotary cutter, slice a piece of the string a little longer than the square. Then place the string on the right side of the square and cut another piece as long as the square and the first cut string.