Are you FMQ on a domestic or log arm machine? Yes, the black is the negative space. Angela does a lot of ruler work on blocks but I don't know if you can do that. If you can, a diamond shape would be nice in each of the 4 patch patches.
If you are looking for a single FMQ design for each blocks, I might try the Square Flower design for http://www.theinboxjaunt.com/ She has in in a 6 inch square but you could downsize it to 4 inch for each of the 4 patches or upsize it to do the whole block. I also like to do an orange peel design using the sides of 4 patch squares and that would look good also I think.
You can find all her designs by clicking on the quilt/tutorial button at the top under the title and then click on the quilting tutorial (motifs) section.
Last edited by Tartan; 02-06-2014 at 07:34 AM.