Warhammer 40k Modular building with connectors

I was admiring TruFords excellent remix of flameblade's excellent model, when it occured to me that if I was actually to put this together and use it for a game, I'd be worried about it sliding or even falling.

So I tweaked the model very slightly to add two options for negating that risk:

* "Pegs" - 4mm diameter, 2mm high cylinders on the top of the base and middle piece, which mate to 5mm diameter, 3mm deep holes on the bottom of the middle and top piece.
* Magnets - 5mm diameter, 3mm