Quite simple but useful expression for after effects which creates 3d text by offsetting layer every 1 unit in Z axes. It uses first layer index value which should be on top of stock.
Here is a expression which should be put in position parameter
offset = index -1;
p = thisComp.layer("your_layer_name");
After duplicating this basic layer the next will be offseted by 1 unit in space. Just copy around 15 to 20 layers and you will have 3D looking text in After Effects.