Firstly, you're South Park afghan is sooooooo neat!! Love it!
Ok, I used a size J cabled afghan hook. (Hobby Lobby sells them. Or order one from Jo Ann Fabrics). J is my favorite size hook to use. Not too small so the stitches are tight, and not too large so your afghan looks "holy" (or full of holes). It makes a nice solid picture.
Ok, I did the afghan in three panels. The top three Marilyns are one panel, then the middle three Marilyns were another, then the bottom three Mds.
Then, I single crocheted around each panel twice. Once in the yellow, and once in the black.
Then I joined the top to the middle and the middle to the bottom panels. (Single crocheting front loops only from front to back. All the way around. I wanted to make sure these babies don't seperate. You can see a line going across but it's in black and not very noticeable.
Then, single crocheted around the entire thing twice. I would have done more, but it's sooo heavy already and I wanted it to look like picture frames. If I made the outside border too wide, each picture "frame" wouldn't look properly square.
Anyway, it still wants to curl a bit. One photo in my blog shows it curling a bit one one side because it was so windy when I was taking the pics. I'm hoping with time it will "settle down" now that it's been crocheted into something and the yarn will relax.