How do I turn a model into an action figure?

Posted in Custom Workstation

I have been inspired by e-freeze custom Guyver figure made from a Guyver model kit and a spiderman figure. I have ordered the model kit and am waiting for it to arrive, in the meantime I would like any advice on how I should go about turning the model into a poseable figure. I have no experiance with model kits though I have been customizing for a little while now. I am under the impression the model kits are hollow. What should I use to fill the space between the vinyl model and the limbs of the figure I will donate to add articulation? Any help on this would be...... well helpful. Thanks for any advice you can offer, hopefully e-freeze might see this and let me in on his secrets that produced his awesome Guyver figure.