I've been using the 3D Box object to make a Tomba-like 2.5d platform prototype and I had a few suggestions:
1. Allow access to all of the object's attributes in the event sheet editor. Right now I can change a box's z coordinate to make neat-looking platforms that move in and out on the z axis, but since the "base" of the box is still on the same z plane as the player sprite, I have to fake solidity with a separate, invisible sprite that overlaps onto the 3D Box when the box body is within a certain z range. If I could just toggle the 3D Box's own "solid" attribute from the event sheet editor it would make things a lot easier, more efficient, and less cluttered. (I notice there is something similar to this with the sprite object in that you can change it's Collision Mode in the even sheet.)
2. Perhaps a feature in conjunction with the textures that allow you to tile a texture on a face, either for X, Y, or both? This could cut down on huge texture files. An example of how the user might implement this:
3. Would it be possible to make a new 3D Sprite object? It would function the same as a 3D Box, but it would have only one face. Instead of texture properties it could use the animator bar the way a sprite does. Since it would have a z property it would render correctly in relation to other 3D Boxes or sprites, but it would otherwise behave like a regular sprite.