No, you are overcomplicating things...it actually drop dead simple. Copy your 3ds files into the assets directory of your project (if there is none, create one). Then, in your Activity, do
getResources().getAssets().open("yourfilename.3ds");
to get the InputStream for the file. You can also put the files into res/raw. Then, it goes like this:
getResources().openRawResource(R.raw.yourfilename);