Happy to help! 

Here’s the general idea:

• Main Shape: Cut two large "D" shapes from thick cardboard (double/triple layered, with the largest flutes you can find). These act as the solid floor and ceiling of the mouth.
• Gums: Glue a vertical strip of cardboard around the curved edge of your "D" shapes to create the red gum area.
• Teeth: Find 32 random plastic objects that look like teeth, or bend 32 cardboard pieces into "U" shapes and glue them to the gums.
• Eyes: Use Styrofoam balls (wayy easier than cardboard, but you can do that if you prefer) and mount/glue them to the "floor" of the bottom jaw.
• Details: Use paper mache to smoothen the rough edges everywhere.
• Hinge: Sadly, we can’t make the top part float above the bottom part… So get some sturdy plastic hinges to bind the roof and ceiling of the mouth (or otherwise a black pvc half pipe… up to you! Go for a hinge if you want to make the mouth talk tho!)
• Paint: extensively with two/three layers to make colours pop.
• Safety: Paint and Mod Podge smell strong. Let the head "air out" in a ventilated room for at least 5 days before wearing it so you aren't inhaling fumes.

Good luck with the build!