Chris, at DSM we only need low-resolution (72dpi) versions of your layouts because they are reviewed onscreen. We also don't need the layouts submitted full-size. Submitting a 12x12 original layout as a 6x6 lo-res version works fine. There is a 100K size limit and saving a 6x6 at about 60% should get you in under that with no problem at all. If your layout is chosen for publication we will ask you to submit an 8x8 hi-resolution version for print purposes.
Hope this helps!
