Got file loading working. Had to fix STLoader in three.dart and then add a method to load models from local file via chrome filesystem apis.
As you can see, as I slice down, support material only appears under areas that need it. I still need to handle cases where a feature hangs low outside the support matrix, but for simple shapes, like Modio action figure parts, this should work fine. Next up is providing the ability to move models around, etc.