Look up soft robots. I was inspired by this paradigm
The material is cheap and reusable (just remelt!) and it's a simple solution to complex actions such as picking an object up without crushing it. Normally with hard robots you need many sensors and it needs a big "brain" to calculate everything and the actuators need precision.
Think of evolution. invertebrates are simpler yet they still exist because although they are simple they are robust. Go this route.
If you want a mobile gynoid, the simplest way would to be to probably make it basically a 100% soft skeleton, like a hydro skeleton and soft pneumatic actuators. Then for structure add armored plated like an exoskeleton (this makes it look like a stereotypical sci-fi gynoid). Then for stability suspend it with a cable between it's shoulders. It needs power (electricity and compressed air) so it really shouldn't be a problem. It's very practical. I took a solder to my 100cm sex doll and ripped out the skeleton. I'm working on Posing it with pneumatics. Sex Dolls have stiff joints (so it doesn't recoil like a Biotrash ) and posing is a bitch. I'm hoping to fix these 2 problems. although It's too flexible at the moment without any skeleton at all.
For you, you can probably get away with a hollow inflatable Japanese sex doll as the outer layer for experimenting with the design before going all out. They are just under $200 dollars.
And you can use a 3d printer with flexible silicone threading to print soft actuators so you don't need to cast a mold for every experiment.