The idea is to use standard Terra-Blocks and the supply floors / roofs which use the same concept as our Warchest Lids, i.e. a lip top and bottom to hold firmly in place.
We would make these available in a wide number of sizes from 150mm x 150mm upwards in 50mm increments in various shapes (square / rectangular, L, T, H).
Multi-story buildings with detailed, but more importantly changeable interiors could then be constructed that can be lifted apart without risk of slippage during play.
This would be too expensive to do for every building on your table, and unnecessary to, but for the key objective buildings that you are going to be fighting through, it opens up a lot of possibilities.