A pretty long but thorough video about where to find and turn in all of the skulls for the Developer's Crafts. Assuming you're far enough in the game and haven't got any of the skulls you'll be picking them up in this order:
Pick up Purple Skull
Drop off Purple Skull
Pick up Blue Skull
Pick up Brown Skull
Drop off Brown Skull
Drop off Blue Skull
Pick up Green Skull
Pick up Orange Skull
Drop off Green Skull
Drop off Orange Skull
Done!
If you guys have any questions, let me know. Otherwise it's time to see what I can put together for Battlefield 3. Any suggestions? :P