You can use a regular sewing machine for all of the steps.
You can also use a serger to do most everything except adding details where you need a straight or zigzag stitch. You can look at the Robohoodie for American Girl Dolls
for more info on using a serger.
This project does not require any expensive foam pieces or core shapes. You do not need to deal with toxic foam bits from cutting and sanding or need to use toxic glues.
All you need is:
- fabric material of any kind
- a bit of cardboard
- a sewing machine
- a serger if you have one
- an imagination
I had a few sheets of pre-cut felt and robo-yellow fleece laying around. All of these dimensions were created as we went along to fit. Next one I make will probably be smaller and sized to be easily manipulated by a child-sized hand and arm.
I folded over that sheet of black felt to make the top and bottom of the mouth. Add a piece of red felt shaped like a tongue.
Cut out matching pieces of some other material to match. This is to form 2 pockets for the top and bottom of the mouth. Later on we will slip in cardboard stiffeners and that is where you place your hands to animate the mouth. I serged the edge of fabric for the pocket opening.
Sandwich everything and serge around the half-moon shape. Cut out carboard stiffeners to fit in the pockets. Test fit and take out to make the rest of the sewing easier.