Just starting to think out loud and wanted some thoughts.
What about where you would take a pearler bead pattern, and turn that into a center block for a afgan? So a pattern is picked, the colors divided up, and then each makes all the people in the swap that color. (Thinking would have to be evened out, so the person with the main color did not get stuck with a ton and the one with black gets 10 to make)
Then these could be made into a center point or a block for the afgan.