We had a super-amazing church costume party on the weekend and here's how we went:
No sewing at all- my favorite. I cut the bellies out of fleece (you could use felt) and used quilters temporary spray glue to stick it to green shirts. I drew the lines with a brown fabric marker. Franklin's hat is a team hat that I covered with felt and adhered with the same spray glue.
My Mrs. Turtle necklace is made of purple ribbon and a wooden circle painted white. Felt or a button would work for the charm as well. I used sticky velcro on the ends so it can come apart and hot glued the circle onto the ribbon.
We both had turtle-shell backpacks. One is a vintage ninja turtles backpack (doubles as a candy bag!) and the other was a handmade fleece kijiji find. I think one could definitely be made from fleece, hot glue, straps and stuffing in no time.
My little Franklin is just too cute!