I asked Allen of GameCraft Miniatures to make some laser cut/etched building bases for all the E40k ruins I have. There were three sizes overall: 12x12, 12x30 and 30x30cm. I went with those sizes for a couple of reasons. For one, they all fit together nicely on a 4x6' board if you assume 6cm spaces (roads that will fit titan bases) between them. You effectively get a 7x10 placement grid for the 12x12cm pieces, and the bigger pieces can replace 2 or 4 adjacent pieces.
Also, the 12x12 pieces allows for the bigger square ruins on it with enough room for the E40k strip bases all around. That's what the etched sidewalk pattern is for. The ruins fit snugly in the big center square and the sidewalk that goes around can hold a strip base (it's about 1/2" or 13mm wide). All in all I'm pretty happy with how they came out.
