Low cost turtle costume, that takes some time, but isn't very difficult.
Step 1: Starting Off
-Buy or dye green sweats
-Print inspiration from the web (or use this instructable).
-Make sketch of turtle approximate size that you want.
-Make xeroxes of sketch.
Step 2: Making the Shell
-Paper mache basic front and back pieces.
-Let back shell dry on a round or curved object.
-Cut sections of back shell off of xeroxes progressively smaller.
-Paper mache these on the back. Making them smaller with give a more realistic 3D look to the shell.
-Paint patterns on shell. I used beige, brown, white and yellow paint plus a black sharpie.
Step 3: Fleece
-Cut one piece of fleece at least waist length.
-Cut hole for head.
-Cut/ sew elastic on sides. I made fleece sleeves for the elastic, but this step can be skipped.
-Cut/ sew velcro onto fleece.
I recommend fleece, because you don't have to hem it after you cut it and it doesn't run like felt.
You can also make this a no sew project by using velcro that you can iron onto the fleece and by cutting pieces of fleece to attach the sides together.
Step 4: Last Steps
-Glue velcro to shell
-Attach shell to fleece.