You will need:
1 case for orthodontic retainer (for the head. You can replace it with a computer mouse, but it will be more tricky to build the mouth)
Plastic caps and cases from shaving foam, liquid detergents, beverage and other plastic stuff (look at the picture)
Screws, nuts and rings
2 plastic circles (for the eyes. I use two from alcoholometer mouthpieces)
Red rubber or EVA foam (for the tongue)
For the arms, I use pieces from a damaged Transformer (the legs of an Animated Bumblebee)
Dremel Rotary Tool
And don't forget:
1. If you don't have it, replace it!
2. Use protective equipment (dust mask and goggles)
3. Beware of drilled and soldered hot surfaces
4. Work in a good ventilated area.
5. Always have junk in stock