Another test, this time using a glass base mat.

The only things that appear to work from scratch painted on all sides are rocks. This may be because they have a pre-set to be sunk part-way into a surface. The middle cube has rocks painted onto several sides.

With a glass base you can see that the plants on the right hand cube grow on the base (the original top) and the ones painted on the bottom, grow inside. The rocks appear above and below the surfaces.

Other objects seem to behave like plants, vertical in the direction Vue has decided is up. So those painted on the bottom, grow within the cube - the houses on the lefthand cube. Tried to add some objects on one of the narrow sides but they still came out perpendicular to the original base. So I made them Perpedicular rather than Vertical to the surface (slider in Scaling and Orientation tab). They came out upon that surface (top of left cube in picture).

Definite possibilities for surrealism though.

Jane