Can I resize a fbx to fit within a UI button in 4.6?

I am letting the user choose their gender. I have an fbx model for both male and female. I am trying to scale the models to fit inside each button since the buttons are set up to scale to fit different resolutions/aspect ratios. I can find the width and height of the button using maleButton.rect.height in pixels. Now how do I scale the fbx’s to fit inside those pixel dimensions?

There may be a way but you’d be far better getting a screen grab of the model and using it as an image for the button, unless you actually want it animated.