How can I change the color and other material properties of certain elements of a 3D Collada model in Studio (for e.g.: re-color a plastic bottle and its cap)?
You can do this in Studio (either Designer Quality or Visualizer Quality) by selecting elements from the 3D model using the Material Selector (right underneath the Scene drop-down menu) or by simply selecting the elements in the Studio Window (ALT/OPTION + Click to select underlying or hidden materials). As soon as a part without print model is selected, you'll get some specific appearance options for that material.
In Designer Quality, you will be able to remove a texture image or tweak the color as well as change the highlight intensity and sharpness. In Visualizer Quality, you will have two additional options: changing the Transparency and tweaking the HighlightColor.
Select the material part of the model, for example: Cap of the bottle. In Visualizer Quality you can change Color, Transparency, Intensity, Sharpness etc.
If there are multiple material parts on a model, you can directly click and select it in Studio or click the Next button in the left top corner (Material Editor).
In order to see the above material options in the Studio Designer window, you'll need to enable the Show Options feature from the Studio Window's flyout menu.