Now that I have 3D-modelled the electronics modules stack, it seems it can fit in the back half of the body, behind the motors. Not represented here is a mess of wires connecting the interface modules with motors, servos, power supply. Anyway there's still some room left in the front half. Maybe I can add a 0.95" oled display for instance (the greyish cutout in the torso), and speaker with wav/mp3 module?

Additionnally, I'm not fully satisfied with the accuracy of my hand-sawn plywood parts, so I intend to rebuild the whole body out of laser cut plywood or MDF. If I use yellow tainted MDF instead of plywood, I could probably have burn additional aesthetic details on the surface. 

I have no experience in laser cutting & drawing though. Can anyone give me some advice on how to design and assemble a beautiful body?