Sliding Doors

Hi -

I'd like to create some sliding doors which will open and close in the middle, revealing and hiding the compositions behind them.

I'd like these to open side to side, and then top to bottom, maybe at an angle as well, and finally as four corner pieces closing in the middle.

When using 2d layers, I can simply draw a mask down the middle and cut a single rectangle into two perfectly interlocking sides - whether I'm using a straight line or creating a jagged edge with interlocking angles or teeth. 

The problem is I'd like to have some thickness to the doors as well, which would require making layers 3d so I can extrude them.

I tried doing this with Shape layers and setting to 3d, but can't seem to mask those.

And if I put the 3d shape layer into a precomp so i can mask it, i seem to lose the extrusion.

May try this in cinema 4d lite, but would like to know if there's a way to do this within After Effects itself (and if i'm just messing up some simple step)

Thanks for any suggestions.